SQL Practical Questions/Answers

Create a new database named “company”.

Answer: CREATE DATABASE company;

Create a table named “employees” with columns for id (integer, primary key), name (varchar), age (integer), and department (varchar).

Answer: CREATE TABLE employees (id INT PRIMARY KEY, name VARCHAR(255), age INT, department VARCHAR(255));

Create a table named “products” in the “company” database with columns for id (integer, primary key), name (varchar), price (decimal), and quantity (integer).

Answer: CREATE TABLE company.products (id INT PRIMARY KEY, name VARCHAR(255), price DECIMAL(10, 2), quantity INT);

Alter the “employees” table to add a new column named “salary” (integer).

Answer: ALTER TABLE employees ADD COLUMN salary INT;

Alter the “products” table to add a new column named “description” (text).

Answer: ALTER TABLE company.products ADD COLUMN description TEXT;

Alter the “products” table to modify the data type of the “price” column to FLOAT.

Answer: ALTER TABLE company.products MODIFY COLUMN price FLOAT;

Alter the “products” table to rename the column “quantity” to “stock”.

Answer: ALTER TABLE company.products RENAME COLUMN quantity TO stock;

Drop the “salary” column from the “employees” table.

Answer: ALTER TABLE employees DROP COLUMN salary;

Insert a new record into the “products” table in the “company” database with values for id, name, price, and stock.

Answer: INSERT INTO company.products (id, name, price, stock) VALUES (1, 'Laptop', 999.99, 50);

Insert multiple records into the “products” table in the “company” database with values for id, name, price, and stock.

Answer: INSERT INTO company.products (id, name, price, stock) VALUES (2, 'Smartphone', 499.99, 100), (3, 'Tablet', 299.99, 75), (4, 'Headphones', 99.99, 200);

Insert a new record into the “employees” table with values for id, name, age, and department.

Answer: INSERT INTO employees (id, name, age, department) VALUES (1, 'John', 35, 'HR');

Insert a new record into the “employees” table with values for id, name, age, department, and salary.

Answer: INSERT INTO employees (id, name, age, department, salary) VALUES (4, 'Alice', 28, 'Marketing', 50000);

Update the price of the product with id 2 to 549.99 in the “products” table.

Answer: UPDATE company.products SET price = 549.99 WHERE id = 2;

Update the stock of the product with id 1 to 40 and its price to 899.99 in the “products” table.

Answer: UPDATE company.products SET stock = 40, price = 899.99 WHERE id = 1;

Update the age of the employee with id 1 to 30 in the “employees” table.

Answer: UPDATE employees SET age = 30 WHERE id = 1;

Update the department of the employee with id 2 to ‘Finance’ in the “employees” table.

Answer: UPDATE employees SET department = 'Finance' WHERE id = 2;

Delete the record with id 3 from the “products” table in the “company” database.

Answer: DELETE FROM company.products WHERE id = 3;

Delete all records from the “products” table where the price is less than 100.

Answer: DELETE FROM company.products WHERE price < 100;

Delete all records from the “products” table.

Answer: DELETE FROM company.products;

Delete all records from the “employees” table where the age is greater than 50.

Answer: DELETE FROM employees WHERE age > 50;

Delete the employee with id 3 from the “employees” table.

Answer: DELETE FROM employees WHERE id = 3;

Select all columns from the “employees” table.

Answer: SELECT * FROM employees;

Select only the “name” and “age” columns from the “employees” table.

Answer: SELECT name, age FROM employees;

Select all employees from the “employees” table where the department is ‘IT’.

Answer: SELECT * FROM employees WHERE department = 'IT';

Select all employees from the “employees” table where the age is between 25 and 35.

Answer: SELECT * FROM employees WHERE age BETWEEN 25 AND 35;

Select all employees from the “employees” table sorted by age in ascending order.

Answer: SELECT * FROM employees ORDER BY age ASC;

Select the oldest employee from the “employees” table.

Answer: SELECT * FROM employees ORDER BY age DESC LIMIT 1;

Retrieve unique values from the “department” column in the “employees” table.

Answer: SELECT DISTINCT department FROM employees;

Retrieve the first 10 records from the “orders” table, ordered by the “order_date” column in descending order.

Answer: SELECT * FROM orders ORDER BY order_date DESC LIMIT 10;

Find the total number of records in the “products” table.

Answer: SELECT COUNT(*) FROM products;

Update the “price” column of the “products” table to 50 where the “category” is ‘Electronics’.

Answer: UPDATE products SET price = 50 WHERE category = 'Electronics';

Delete all records from the “employees” table where the “department” is ‘HR’.

Answer: DELETE FROM employees WHERE department = 'HR';

Retrieve the average salary of employees from the “employees” table.

Answer: SELECT AVG(salary) FROM employees;

Find the highest salary from the “employees” table.

Answer: SELECT MAX(salary) FROM employees;

Retrieve the names of employees who have joined after ‘2020-01-01’.

Answer: SELECT name FROM employees WHERE join_date > '2020-01-01';

Retrieve the second highest salary from the “employees” table.

Answer: SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees);

Calculate the total sales amount for each product from the “sales” table and group them by product ID.

Answer: SELECT product_id, SUM(amount) AS total_sales FROM sales GROUP BY product_id;

Retrieve all orders where the order amount is greater than $1000 from the “orders” table.

Answer: SELECT * FROM orders WHERE order_amount > 1000;

Find the number of orders placed by each customer from the “orders” table and group them by customer ID.

Answer: SELECT customer_id, COUNT(order_id) AS order_count FROM orders GROUP BY customer_id;

Find the top 5 best-selling products from the “products” table based on the quantity sold.

Answer: SELECT product_id, SUM(quantity_sold) AS total_quantity FROM products GROUP BY product_id ORDER BY total_quantity DESC LIMIT 5;

Retrieve all columns from the “employees” table where the salary is greater than $50000.

Answer: SELECT * FROM employees WHERE salary > 50000;

Find the total number of customers from the “customers” table.

Answer: SELECT COUNT(*) FROM customers;

Retrieve the names and ages of customers from the “customers” table who are older than 30 years.

Answer: SELECT name, age FROM customers WHERE age > 30;

Update the “status” column of the “orders” table to ‘Completed’ where the “order_date” is before ‘2023-01-01’.

Answer: UPDATE orders SET status = 'Completed' WHERE order_date < '2023-01-01';

Delete all records from the “products” table where the “category” is ‘Books’.

Answer: DELETE FROM products WHERE category = 'Books';

Retrieve the names and email addresses of customers from the “customers” table where the email address contains ‘@gmail.com’.

Answer: SELECT name, email FROM customers WHERE email LIKE '%@gmail.com%';

Find the average salary of employees in the “sales” department from the “employees” table.

Answer: SELECT AVG(salary) FROM employees WHERE department = 'Sales';

JavaScript Practical Questions

  1. Write a JavaScript function to add two numbers.
  2. Create a function to subtract two numbers.
  3. Write a function to multiply two numbers.
  4. Create a function to divide two numbers.
  5. Write a JavaScript function to find the square of a number.
  6. Create a function to find the cube of a number.
  7. Write a JavaScript function to find the maximum of two numbers.
  8. Create a function to find the minimum of two numbers.
  9. Write a function to check if a number is positive, negative, or zero.
  10. Create a JavaScript function to check if a number is even or odd.
  11. Write a function to check if a number is a multiple of another number.
  12. Create a JavaScript function to check if a year is a leap year.
  13. Write a function to calculate the area of a rectangle given its length and width.
  14. Create a function to calculate the perimeter of a rectangle given its length and width.
  15. Write a JavaScript function to calculate the area of a circle given its radius.
  16. Create a function to calculate the circumference of a circle given its radius.
  17. Write a function to convert Celsius to Fahrenheit.
  18. Create a JavaScript function to convert Fahrenheit to Celsius.
  19. Write a function to generate a random integer between two specified values.
  20. Create a function to generate a random number between 0 and 1.
  21. Write a JavaScript function to generate an array of specified lengths filled with random integers.
  22. Create a function to find the factorial of a given number.
  23. Write a JavaScript function to check if a given number is prime.
  24. Create a function to find the sum of all numbers in an array.
  25. Write a function to find the average of numbers in an array.
  26. Create a JavaScript function to find the largest element in an array.
  27. Write a function to find the smallest element in an array.
  28. Create a function to find the median of numbers in an array.
  29. Write a JavaScript function to reverse a string.
  30. Create a function to check if a given string is a palindrome.
  31. Write a function to count the number of vowels in a string.
  32. Create a JavaScript function to count the number of words in a sentence.
  33. Write a function to find the longest word in a sentence.
  34. Create a function to remove duplicates from an array.
  35. Write a JavaScript function to sort an array of numbers in ascending order.
  36. Create a function to shuffle elements in an array.
  37. Write a function to truncate a string to a specified length.
  38. Create a JavaScript function to capitalize the first letter of each word in a sentence.
  39. Write a function to find the difference between two dates in days.
  40. Create a function to check if two arrays are equal.
  41. Write a JavaScript function to find the intersection of two arrays.
  42. Create a function to merge two sorted arrays into one sorted array.
  43. Write a function to remove a specific element from an array.
  44. Create a JavaScript function to remove all false values from an array.
  45. Write a function to find the most frequent element in an array.
  46. Create a function to check if an array contains a specific value.
  47. Write a JavaScript function to flatten a nested array.
  48. Create a function to rotate elements in an array to the left by a given number of positions.
  49. Write a function to generate a Fibonacci sequence up to a specified number of terms.
  50. Create a JavaScript function to check if a string contains unique characters.\

C Programming Practical Questions

  1. Write a C program to find the sum of two numbers using a function.
  2. Create a program to calculate the factorial of a number using a function.
  3. Write a C program to check if a number is prime using a function.
  4. Create a program to find the maximum of two numbers using a function.
  5. Write a C program to reverse a string using a function.
  6. Create a program to swap two numbers using call by reference.
  7. Write a C program to sort an array of integers using functions.
  8. Create a program to find the length of a string using a function.
  9. Write a C program to concatenate two strings using functions.
  10. Create a program to find the square of a number using a function.
  11. Write a C program to implement a structure representing a student with fields for name, roll number, and marks in three subjects.
  12. Create a program to calculate the average marks of a student using a structure.
  13. Write a C program to display details of students stored in an array of structures.
  14. Create a program to find the student with the highest marks using structures.
  15. Write a C program to implement a union representing the details of an employee with fields for employee ID, name, and salary.
  16. Create a program to display details of employees stored in an array of unions.
  17. Write a C program to find the employee with the highest salary using unions.
  18. Create a program to swap two numbers using pointers.
  19. Write a C program to reverse an array using pointers.
  20. Create a program to find the sum of elements in an array using pointers.
  21. Write a C program to find the length of a string using pointers.
  22. Create a program to concatenate two strings using pointers.
  23. Write a C program to implement a linked list to store integers.
  24. Create a program to insert a node at the beginning of a linked list.
  25. Write a C program to insert a node at the end of a linked list.
  26. Create a program to delete a node from a linked list.
  27. Write a C program to search for a node in a linked list.
  28. Create a program to reverse a linked list.
  29. Write a C program to implement a stack using an array.
  30. Create a program to push an element into a stack.
  31. Write a C program to pop an element from a stack.
  32. Create a program to implement a queue using an array.
  33. Write a C program to enqueue an element into a queue.
  34. Create a program to dequeue an element from a queue.
  35. Write a C program to implement a stack using linked list.
  36. Create a program to push an element into a stack implemented using linked list.
  37. Write a C program to pop an element from a stack implemented using linked list.
  38. Create a program to implement a queue using linked list.
  39. Write a C program to enqueue an element into a queue implemented using linked list.
  40. Create a program to dequeue an element from a queue implemented using linked list.
  41. Write a C program to copy contents of one file to another.
  42. Create a program to count the number of characters, words, and lines in a file.
  43. Write a C program to find the largest word in a file.
  44. Create a program to append text to a file.
  45. Write a C program to merge two files into a third file.
  46. Create a program to sort lines of text in a file alphabetically.
  47. Write a C program to encrypt and decrypt text in a file.
  48. Create a program to find and replace a word in a file.
  49. Write a C program to search for a specific line in a file.
  50. Create a program to display the contents of a file in reverse order.

PHP Practical Questions

  1. Write a PHP script that connects to a MySQL database and inserts user input from a form into a database table.
  2. Create a PHP script that retrieves user input from a form using the POST method, performs a calculation, and displays the result.
  3. Write a PHP script that retrieves user input from a form using the GET method, performs a database query based on the input, and displays the results.
  4. Create a PHP script that connects to a MySQL database, retrieves user input from a form, updates a specific record in the database based on the input, and displays a success message.
  5. Write a PHP script that connects to a MySQL database, retrieves user input from a form using both POST and GET methods, performs a calculation based on the input, and displays the result.
  6. Create a PHP script that retrieves user input from a form, validates the input, performs a database query to check if the input exists in the database, and displays appropriate messages.
  7. Write a PHP script that connects to a MySQL database, retrieves user input from a form using the POST method, inserts the input into multiple database tables, and displays a success message.
  8. Create a PHP script that retrieves user input from a form using the GET method, performs a database query to fetch relevant data based on the input, and displays the data in a formatted manner.
  9. Write a PHP script that connects to a MySQL database, retrieves user input from a form using the POST method, performs a calculation based on the input, and updates the result in the database.
  10. Create a PHP script that retrieves user input from a form using the GET method, performs a database query to fetch relevant data based on the input, calculates the total based on the retrieved data, and displays the total to the user.

DBMS Viva Question

What is the difference between Data and Information?

What do you mean by  Field, Attribute, Record, Table, and Database?

What is a Database Management System?

What are the types of keys in DBMS?

What are the advantages of DBMS over Excel?

Differentiate between DDL and DML.

What is SQL?

What is the purpose of SQL?

What is the purpose of the SELECT statement in SQL?

What is the meaning of * in Select Statement in SQL?

What is the difference between DELETE and Drop commands?

What is the difference between DELETE and TRUNCATE commands?

What is the purpose of the WHERE clause in SQL?

What is the purpose of the INSERT statement in SQL?

What is the purpose of the UPDATE statement in SQL?

What is the purpose of the DELETE statement in SQL?

What is the purpose of the ORDER BY clause in SQL?

JavaScript Viva Question

What is client-side scripting, and how does it differ from server-side scripting?

Name some popular client-side scripting languages.

How do we create comments in JavaScript?

In JavaScript, you can create comments using two different methods:

Explain about Global and Local Variable.

     Global Variables:

     Local Variables:

Differentiate between null and undefined.



How do you create an array in JavaScript?

Explain the concept of event handling in client-side scripting.

What is JavaScript, and how does it enhance web development?

Explain the various methods to include JavaScript code in an HTML page.

What are the different attributes of the <script> tag, and how do they affect script execution?

Discuss the placement of <script> tags within an HTML document and its implications.

Explain the concept of inline JavaScript and its advantages and disadvantages.

Explain how to use JavaScript to manipulate HTML elements and modify the content and style of a web page.

Explain the difference between JavaScript and Java.

What are the basic building blocks of JavaScript programs?

What are data types in JavaScript?

Discuss the role of type coercion in JavaScript and provide examples.

What is a variable in JavaScript, and how do you declare one?

Explain the rules for naming variables in JavaScript.

Discuss the difference between var, let, and const for declaring variables.

Explain the concept of hoisting in JavaScript variable declaration.

What are operators in JavaScript, and what categories do they fall into?

Discuss the difference between unary, binary, and ternary operators, providing examples of each.

Explain the use of arithmetic operators in JavaScript with examples.

Discuss the importance of operator precedence and associativity in JavaScript expressions.

Explain the use of comparison operators and logical operators in JavaScript with examples.

What are the various pop-ups in JavaScript?

In JavaScript, you can create various types of pop-ups to interact with users.


                                var result = prompt("Enter your name:", "");
                                var result = confirm("Are you sure?");

Differentiate between console.log() and document.write()?

                                    console.log("Hello, world!");

document.write("<h1>Hello, world!</h1>");

How do we convert a string with numeric value to integer data type?

parseInt() and Number() are both functions in JavaScript used for converting values to numbers.

What is a function in JavaScript?

How do you declare a function in JavaScript?

Explain the difference between function declarations and function expressions.

What are the parameters and arguments in a function?

Explain the concept of return values in functions.

What is the if-else statement, and how is it used in JavaScript?

Explain the syntax and usage of the if-else-if statement in JavaScript.

How do you use the switch-case statement in JavaScript?

What are the types of loops in JavaScript?

Discuss the syntax and usage of the for loop in JavaScript.

Explain the syntax and usage of the while loop in JavaScript.

How do we create exception handling in JavaScript?

In JavaScript, you can perform exception handling using try, catch, and finally blocks.

          try {

                var result = 10 / 0; // This will throw a division by zero error

                console.log(result); // This line won’t be executed }

          catch (error) {

                console.error(“An error occurred:”, error); }

          finally {

                console.log(“Execution completed.”); // This line will always be executed


Explain the concept of objects in JavaScript.

How do you create objects in JavaScript?

What are events in JavaScript, and how are they triggered?

How do you handle events in JavaScript?

What is the Image object in JavaScript?

How do you create an Image object in JavaScript?

What properties and methods does the Image object provide?

What is the Form object in JavaScript?

How do you access a Form object in JavaScript?

What properties and methods does the Form object provide?

What is form validation, and why is it important in web development?

Explain the difference between client-side and server-side form validation.

What are some common techniques for client-side form validation in JavaScript?

What is jQuery, and how does it simplify DOM manipulation and event handling?

How do you include jQuery in a web page, and what is the jQuery syntax for selecting elements?

C Programming Viva Question

What is a function in C programming?

What is the purpose of using functions in C?

How do you define a function in C?

What is the difference between a function declaration and a function definition?

What is a function prototype in C?

What is the difference between a library function and a user-defined function?

What are the advantages of using functions in programming?

What are function parameters?

How are function parameters passed in C?

What is the difference between call by value and call by reference?

How do you specify the return type of a function in C?

Can a function return multiple values in C?

What is recursion in C?

What are the necessary conditions for recursion?

How does recursion work in C?

What is a structure in C programming?

How do you define a structure in C?

What is the difference between structure definition and declaration?

How do you initialize a structure in C?

How is the size of a structure calculated in C?

How do you access members of a structure in C?

What is an array of structures in C?

What is a union in C programming?

How do you define a union in C?

What is the difference between a union and a structure in C?

What is a pointer in C programming?

What is a data file in C programming?

What is the purpose of using data files in programming?

What is a sequential file?

What is a random file?

What is the purpose of putw() and getw() functions in C?

Explain the usage of putc() and getc() functions in C.

What are fscanf() and fprintf() functions used for in C?

How do you open a file in C for reading?

What is the difference between writing and appending to a file?

How do you close a file in C after reading or writing?

PHP Viva Questions

What is server-side scripting, and how does it differ from client-side scripting?

Name some popular server-side scripting languages.

How does a server-side script interact with a web server?

Explain the typical workflow of a server-side script.

What are the advantages of server-side scripting?

What are the hardware and software requirements for running PHP?

Explain the concept of object-oriented programming in PHP.

What is the basic syntax of PHP?

What are the various data types supported by PHP?

Discuss the different types of operators in PHP.

How do you manipulate variables in PHP?

Explain database connectivity in PHP.

What are the steps involved in connecting a server-side script to a database in PHP?

How do you make SQL queries in PHP?

What does fetching data sets mean in PHP?

How do you create an SQL database using server-side scripting in PHP?

Discuss the process of displaying queries in tables using PHP.

How do you define a class in PHP?

What is the significance of the ‘new’ keyword in PHP?

Explain the difference between == and === operators in PHP.

How do you declare and initialize variables in PHP?

What is SQL injection, and how can it be prevented in PHP?

Discuss the role of the mysqli and PDO extensions in PHP.

How do you handle errors during database connectivity in PHP?

Explain the concept of inheritance in object-oriented programming with PHP.

What are the different types of loops supported in PHP?

Discuss the role of constructor and destructor methods in PHP classes.

How do you execute conditional statements in PHP?

Explain the concept of method overloading in PHP.

What is the purpose of the php.ini file in PHP?

How do you retrieve data from a form submitted via POST method in PHP?

Explain the process of handling file uploads in PHP.

What are the different types of errors that can occur in PHP scripts?

How do you include external PHP files within a script?

What is the purpose of the ‘use’ keyword in PHP namespaces?

Discuss the concept of autoloading classes in PHP.

Explain the difference between GET and POST methods in form submissions.

What is the purpose of the global keyword in PHP?

How do you handle sessions in PHP?

Explain the concept of method chaining in PHP.

What is the purpose of the header() function in PHP?

Discuss the significance of sanitizing user input in PHP.

What is the purpose of the empty() function in PHP?

Explain the concept of method visibility in PHP classes.

How do you define constants in PHP?

Discuss the role of namespaces in PHP.

What is the purpose of the setcookie() function in PHP?

Explain the difference between require and include statements in PHP.

Artificial Intelligence

AI stands for Artificial Intelligence. It  is a concept of giving human-like intelligence to the machines. Though the computers do their work faster  and better than the human beings,  the intelligence of them is zero  because they just follow the set of  instructions given by the user. In case  of wrong instruction, they do wrong processing. It is because they do not have intelligence  of their own. So, the scientists are in research of giving them artificial intelligence, so that  they can understand the natural languages of the human beings and interact. They can  express their feelings and many more.


Components of AI

Different disciplines contributed their ideas, viewpoint, and techniques to plan the  foundation of Al that acts as components of Al. Some of the major contributions of various  disciplines an given below:

  1. Philosophy: It introduces the concept of logic and methods of reasoning and studying the mind as a physical system. It creates the foundation for learning language, and rationality. It also expresses knowledge-based action to be embedded  into the machine to act with AI
  2. Mathematics: It introduces the concepts of the formal representation of facts and proof, algorithms, computation, and reasoning with uncertain information.
  3. Economics: It introduces the concepts of the formal theory of rational decision.
  4. Neuroscience: It introduces the concepts of mental activity which can be introduced into the machine.
  5. Psychology: It introduces the concepts of the brain as an information processing device and phenomenon of perception and sensory-motor control.
  6. Linguistics: It introduces the concepts of knowledge representation and grammar and how does language relates to thought.
  7. Control Theory and cybernetics: It introduces the concepts of designing the system that maximizes an objective function over time. This is roughly similar to the concepts of Al that behave optimally. It describes how artifacts (objects) can operate  under their own control. That is, it introduces the concept of a self-controlling  machine.
  8. Computer science and engineering: This component introduces the concept of hardware, software, and operating system. Apart from this, it also discusses the programming language and tools used in Al.


Uses/Applications of Al

The potential applications of Artificial Intelligence are abundant (plentiful). They stretch  from the military for autonomous control and target identification, to the entertainment  industry for computer games and robotic pets. Let’s also not forget big establishments  dealing with huge amounts of information such as hospitals, banks, industries, and  insurances, which can use Al to predict customer behavior and detect trends.

  1. Game playing:

General game playing (GGP) and General video game playing (GVGP) is the concept and  designs for artificial intelligence programs to successfully play plenty of games. For video  games, game rules have to be either learned over multiple repetitions by artificial players  or are predefined manually in a domain-specific language and sent in advance to artificial  players. For instance, the GGP of chess, computers are programmed to play these games  using a specially designed algorithm. It was considered a necessary landmark on the way  to Artificial General Intelligence. The first commercial practice of general game-playing  technology was Zillions of Games in 1998.

  1. Speech recognition:

In speech recognition, the input is given to the computer in the form of vibrations  produced by the sound. This is done with the help of an analog to digital converter that  converts the vibrations produced by the sound into digital format.

Then, a set of complex algorithms runs on that data to recognize the speech and return a  text as a result. Depending upon the goal, the end result may vary to some extent. For  example, Google Voice typing converts spoken words into suitable text format while  personal assistants like Siri and Google Assistant take the sound as input and convert it  into both voice and text format, giving output as per the user’s requirement.

  1. Understanding natural language:

Natural language understanding is a branch of artificial intelligence that uses computer  software to take the input in the form of sentences using text or speech. It simply reduces  the gap between humans and computers allowing them to interact easily with each other.

  1. Computer vision:

Computer vision is a field of artificial intelligence (AI), which enables the computer and its  systems to get input in the form of digital images and videos and take action based on the  provided input.

  1. Expert systems:

An expert system is a computer system that mimics or even surpasses the decision-making  ability of a human expert. It is generally designed to solve complex problems by surfing  through bodies of knowledge. It is further divided into two subsystems; the knowledge  base (which represents facts and rules) and inference engine (which applies the rules to  the known facts to deduce new facts).

  1. Robotics:

Artificial intelligence (AI) in robotics is the ability of the computer or the robot to perform  multiple tasks performed by humans, which require human intelligence and discernment.  It gives robots a computer vision to navigate, sense, and calculate their reaction  accordingly For example: Robotic packaging uses various forms of Al for quicker and accurate packaging at a lower price. Likewise, Sophia which is also marked as a “social  robot” is successfully able to mimic social behavior and induce feelings of love in humans.

  1. Theorem proving:

Proving theorems requires high intelligence as many of the practical problems can be cast  in terms of theorems. If knowledge is expressed by logic, proving theorem is reasoning. It  uses various AI techniques such as heuristic search.

  1. Symbolic mathematics:

Symbolic mathematics refers to the manipulation of formulas, rather than doing  arithmetic on numeric values. It is often used in conjunction with ordinary scientific  computation as a generator of programs, used to actually do the calculations.

  1. Robotics:

Artificial intelligence (AI) in robotics is the ability of the computer or the robot to perform  multiple tasks performed by humans, which require human intelligence and discernment.  It gives robots a computer vision to navigate, sense, and calculate their reaction  accordingly For example: Robotic packaging uses various forms of Al for quicker and accurate packaging at a lower price. Likewise, Sophia which is also marked as a “social  robot” is successfully able to mimic social behavior and induce feelings of love in humans.

  1. Theorem proving:

Proving theorems requires high intelligence as many of the practical problems can be cast  in terms of theorems. If knowledge is expressed by logic, proving theorem is reasoning. It  uses various AI techniques such as heuristic search.

  1. Symbolic mathematics:

Symbolic mathematics refers to the manipulation of formulas, rather than doing  arithmetic on numeric values. It is often used in conjunction with ordinary scientific  computation as a generator of programs, used to actually do the calculations.


Cloud Computing

Cloud computing is the use of various services, such as software development platforms,  servers, storage, and software, over the Internet, often referred to as the “cloud”. It is  defined as a type of computing that relies on sharing computing resources rather than  having handle applications. In cloud computing, the word cloud is used to  represent “the Internet,” so the phrase cloud  computing means “a type of Internet-based  computing,” where different services – such as  servers, storage, and applications are delivered  to an organization’s computers and devices  through the Internet. Cloud computing allows  application software to be operated using  internet-enabled devices.


Types of Clouds

Clouds can be classified as public, private, and hybrid. Public cloud is made available to  the general public or a large industry group. Private cloud computing environment resides  within the boundaries of an organization and is used exclusively for the organizational  benefits Hybrid cloud is the combination of both public and private cloud. Sensitive With  this cloud organizations might run non-core applications in a public cloud, while  maintaining core applications and data in a private cloud.

Service Models of Cloud Computing

  1. IaaS (Infrastructure as a Service): In this service, computing infrastructural components like server hardware, storage, bandwidth, and other fundamental computing resources are provided through the cloud.
  2. SaaS (Software as a Service): This service includes complete software on the can access software hosted on the cloud without installing it on the user’s own computer.
  3. PaaS (Platform as a Service): It allows the user to rent virtualized servers and associated services used to run existing applications, or to design, develop, test, deploy and host applications. It provides clients with access to the basic operating software and optional  services to develop and use software applications without the need to buy and manage  the underlying computing infrastructure.


Advantages of Cloud Computing:

Some of the advantages of this technology are:

  1. Cost-efficient: It is probably the most efficient method to use, maintain and upgrade.
  2. Almost unlimited storage: Storing information in the cloud gives us almost unlimited storage capacity.
  3. Backup and recovery: Since, all the data is stored in the cloud, backing it up and restoring the same is relatively much easier than storing the same on a physical device.
  4. Automatic software integration: In the cloud, software integration is usually something that occurs automatically. It also allows us to customize the options with great ease.
  5. Easy access to information: Once the user is registered in the cloud, the user can access the information from anywhere, where there is an Internet connection.
  6. Quick deployment: Once the method of functioning is selected, the entire system can be fully functional in a matter of few minutes.

Disadvantages of Cloud Computing:

Despite its many benefits, as mentioned above, cloud computing also has its  disadvantages.

  1. Technical issues: This technology is always prone to outages and other technical issues. Even the best cloud service providers run into this kind of trouble. Despite keeping up high standards of maintenance.
  2. Security in the cloud: Storing all the sensitive information to a third-party cloud service provider could potentially put the company at great risk.
  3. Prone to Attack: Storing information in the cloud could make the company vulnerable to external threats and attacks.


Big Data

Big Data refers to complex and large data sets that have to be processed and analyzed to  uncover valuable information that can benefit businesses and organizations.  It has features like:

  1. It refers to a massive amount of data that keeps on growing exponentially with time.
  2. It is so voluminous that it cannot be processed or analyzed using conventional data processing techniques.
  3. It includes data mining, data storage, data analysis, data sharing, and data visualization.
  4. The term is an all-comprehensive one including data, data frameworks, along the tools and techniques used to process and analyze the data.

According to Gartner, the definition of Big Data- “Big data is high-volume, velocity, and  information assets that demand cost-effective, innovative forms of information processing  for enhanced insight and decision making.”

Types of Big Data

Big data can be classified as Structured, unstructured, and semi-structured.

  1. Structured: It means that data can be processed, stored, and retrieved in a fixed format. It refers to highly organized information that can be readily and seamlessly stored and accessed from a database by simple search engine algorithms.
  2. Unstructured: It refers to the data that lacks any specific form or structure whatsoever. This makes it very difficult and time-consuming to process and analyze unstructured data.
  3. Semi-structured: It relates to the data containing both the formats mentioned above, that is structured and unstructured data. To be precise, it refers to the data that although has not been classified under a particular repository (database), yet contains vital information or tags that segregate individual elements within the data.

Characteristics of Big Data

The main characteristics of big data are:

  1. Variety: It refers to the variety of data gathered from multiple sources. The variety can be structured, unstructured, or semi-structured.
  2. Velocity: It refers to the speed at which data is being created in real-time. It also comprises the rate of change, linking of incoming data sets at varying speeds, and activity bursts.
  3. Volume: Big Data indicates huge ‘volumes of data that are being generated daily from various sources like social media platforms, business processes, machines, networks, human interactions, etc.
  4. Veracity: It refers to the reliability or trustworthiness of the data. Due to the large volume of data, we have uncertainty about the validity, the accurateness of data.
  5. Value: It refers to the worth of business value of the collected data.
  6. Variability: It refers to the inconsistency of the big data and how the big data can be used and formatted.


Application Areas of Big Data

Major application of big is data is:

  1. Healthcare or Medical sector.
  2. Academia.
  3. Banking.
  4. Manufacturing.
  5. Information Technology (IT).
  6. Retail business.
  7. Transportation.


Advantages of Big Data Processing:

Some of the advantages of big data processing are:

  1. Businesses can utilize outside intelligence while taking decisions.
  2. Improved customer service.
  3. Early identification of risk to the product/services,
  4. Better operational efficiency.
  5. Big data analysis derives innovative solutions. It helps in understanding and targeting customers. It helps in optimizing business processes.

Disadvantages of Big Data Processing:

Despite its many benefits, big data processing has the following disadvantages.

  1. Traditional storage can cost a lot of money to store big data.
  2. Big data analysis is not useful in the short run. It needs to be analyzed for a longer duration to leverage its benefits.
  3. Big data analysis results are sometimes misleading.


Virtual Reality

Virtual reality (VR) is a term that expresses  computer-based simulated environments. Which can perceive as in the real world, as  well as in unreal worlds. The virtual reality environments are primarily concerned with the visual experiences, displayed either on a computer screen or through special stereoscopic displays, but some simulations include additional sensory information, such as sound through speakers or  headphones.

Virtual reality creates such a realistic artificial environment that the s/he should feel as in  the real world. Today the Virtual reality (VR) technology is applied to advance fields of  medicine, engineering, education, design, training, and entertainment.

Some of the application areas of virtual reality are:

  1. It can be used in medical studies to enable students to know the human body.
  2. It can be used in scientific research laboratories so that scientists can easily research a structure.
  3. It can be used in entertainment like games and movies to make the gaming experience more real and to allow individuals to experience adventures under extreme conditions.
  4. It can be used in driving schools as it gives a real look at roads and traffic.
  5. It can be used in military training for the soldiers to get familiar with different areas on the battlefield.

Advantages of Virtual Reality:

Some of the advantages of virtual reality are:

  1. Virtual reality creates a realistic world.
  2. It enables users to explore places.
  3. Through Virtual Reality, users can experiment with an artificial environment.
  4. Virtual Reality makes education easier and more comfortable.

Disadvantages of Virtual Reality:

Some of the disadvantages of virtual reality are:

  1. The equipment used in virtual reality are very expensive.
  2. It consists of complex technology.
  3. In virtual reality environment we can’t move by our own like in the real world.


e-Commerce, e-Medicine, e-Governance


Electronic commerce (e-Commerce) is a process of buying and selling or exchanging  products, services, and information using electronic media. There are many definitions for  electronic commerce that include elements of electronic transactions and the buying and  selling of goods and services online.

e-Commerce is a modern business methodology that addresses the needs of  organizations, merchants, and consumers to cut costs while improving the quality of  manufactured goods, services and increasing the speed of service delivery. More commonly, e-commerce is associated with the buying and selling of products, and  services via computer networks. The main platforms of e-commerce remain the Internet, e-mail, fax, telephone orders.


Classification of e-Commerce

  1. B2B (Business to Business) Sells products or services to other businesses. e.g. www.freemarkets.com
  2. B2C (Business to Consumer) Sells products or services directly to consumers. eg.. www.amazon.com, www.yahoo.com.
  3. C2B (Consumer to Business) Consumer fixes a price on their own, which businesses accept or decline, e.g., www.priceline.com
  4. C2C (Consumer to Consumer) Consumer sells directly to other consumer. e.g. www.ebay.com


Advantage of e-Commerce

Some of the advantages of e-commerce are:

  1. It enables more individuals to work at home, and to do less traveling for shopping, resulting in less traffic on the roads, and lower air pollution.
  2. It allows some merchandise to be sold at lower prices, benefiting less affluent people.
  3. It enables people in Third World countries and rural areas to enjoy products and services which otherwise are not available to them.
  4. Facilitates delivery of public services at a reduced cost, increases effectiveness, and/or improves quality.
  5. It enables consumers to shop or do other transactions 24 hours a day, all year round from almost any location.
  6. It provides consumers with more selections or choices.
  7. It provides consumers with less expensive products and services by allowing them to shop in many places and conduct quick comparisons.
  8. It allows quick delivery of products and services, especially with digitized products. 9. Consumers can receive relevant and detailed information in seconds, rather than in days or weeks walk-around to search a product.
  9. It makes it possible to participate in virtual auctions. It allows consumers to interact with other consumers in electronic communities and exchange ideas as well as compare price-tag.
  10. It facilitates competition, as a result of substantial discounts.
  11. It expands the marketplace to national and international markets. It decreases the cost of creating processing, distributing, storing, and retrieving paper based information.


Disadvantage of e-Commerce

  1. Businesses often calculate return on investment numbers before committing to any new technology. Costs, which are a function of technology, can change dramatically during even short-lived e-commerce implementation projects.
  2. Many companies have had trouble recruiting and retaining employees with the technological, design, and business process skills needed to create an effective e commerce presence.
  3. The difficulty of integrating existing databases and transaction-processing software designed for traditional commerce into the software that enables e-commerce.
  4. Many businesses face cultural and legal impediment (barrier) to e-commerce. Some consumers are still fearful (afraid) of sending their credit card numbers over the  Internet.
  5. Consumers are simply resistant to change and are uncomfortable viewing merchandise on a computer screen rather than in person.



e-Medicine is an online clinical medical knowledge database, which is an approach to  providing health care service to a large number of people spread in different locations. It is mainly beneficial for the people of rural areas with limited or no medical facilities. e Medicine is targeted to provide high-quality healthcare service. It minimizes the time and  cost required for treatment.

e-Medicine usually contains up-to-date, searchable, peer-reviewed medical journals,  online physician reference textbooks, and a complete article database on medical  specialties. This Internet medical library and clinical knowledge base are available to  physicians, medical students, nurses, other health professionals, and patients.

With the use of e-Medicine, doctors and patients who are physically apart can connect so  that patients can share his/her problem with the doctor, and the doctor can suggest  treatment or any test required.



e-Governance is the use of information and communication technology (ICT) to enhance  the access and delivery of government services to benefit citizens, business partners, and  employees. It transforms the traditional government using ICT to make it clear, effective,  and accountable. However, it doesn’t mean that putting more computers on the desks of  government officials is e governance.

Governance is more than just a government website on the Internet. Political, social, economic, and technological aspects determine e-governance. It establishes a relationship between government officials and citizens, providing greater access to government information and services by making the government  accessible online, promoting citizen participation by enabling citizens to interact more conveniently with government officials, such as by  requesting government service and filing required documents through the website,  increasing government accountability by making its operations more transparent, thereby  reducing the opportunities for corruption, and supporting development goals by providing  business, rural and traditionally underserved communities with information,  opportunities, and communications capabilities.

For example,

https://www.nepal.gov.np/, https://www.moe.gov.np/, https://www.moha.gov.np/


Objectives of e-Governance

Some of the objectives of e-Governance are:

⮚ E-Governance refers to the provision of online public services to citizens and  businesses.

⮚ Services for citizens include the registration to government services such as health  care, education, or employment benefits.

⮚ For businesses, E-Governance services can take the form of online alerts for public  procurements or funding opportunities as well as information and support on  applicable legislation in a given sector.

⮚ E-Governance helps to cut down their administrative costs, speed up procedures  and therefore increase efficiency and reactivity.

⮚ It could improve and accelerate administrative efficiency.


Challenges of implementing e-Governance 

The key challenges of implementing E-Governance mainly in developing countries like  Nepal are

⮚ High-speed infrastructure to access the Internet is required.

⮚ Creating trust and transparency of successful delivery of E-Governance service.

⮚ The digital divide exists in developing countries. All the citizens may not have ICT knowledge.

⮚ Network security and protection against viruses, spam, unwanted attacks, etc.

⮚ Online privacy.

⮚ All the citizens may not have access to computing resources.


Mobile Computing

Mobile computing is a generic term describing one’s ability to use technology while moving  as opposed to portable which is only practical for use while deployed in a stationary  configuration. A mobile computing device is created using mobile components, such as  mobile hardware and software. Mobile computing devices are portable devices capable of  operating executing, providing services and applications like a computing device. It is a  computing device used in transit. Users can access data and information from wherever  they are.

Many types of mobile computers have been introduced since the 1990s, including a  wearable computer, PDA, enterprise digital assistant, smartphone, UMPC (Ultra-mobile  PC), Tablet PC.

Features of Mobile Computing Device

Features of Mobile Computing devices are

⮚ It is a portable device that can be used during mobility.

⮚ It has limited processing and storage capability.

⮚ It includes mobile communication, mobile hardware, and mobile software.

⮚ It usually contains a touch screen for providing input.

⮚ It contains an on-screen or virtual keyboard for proving text inputs. However, an  external keyboard can be connected by using the USB port, infrared, or Bluetooth.

⮚ It contains a camera, speaker, and microphone.

⮚ It contains handwriting recognizing software.

⮚ Most mobile computing devices contain a memory card slot to expand the storage  capacity.

⮚ It has wireless connectivity such as Bluetooth, Wi-Fi to connect the Internet or with  other computing devices as well as a wired connection through the USB port  connectivity services like need either Wi-Fi.

⮚ The most mobile computing device can synchronize their data with applications on  users’ computers.

⮚ It can be used for cloud computing and remote access.

⮚ It uses a mobile computing operating system such as Android, iOS, Windows Mobile  OS, Palm OS.

⮚ It can include GPS (Global Positioning System) receiver for navigation.


Advantages of Mobile Computing

Advantages of mobile technology are:

⮚ It enables users to work from any location at any time.

⮚ It saves time for accessing data and information.

⮚ It helps to increase the productivity of users reducing the time and cost.

⮚ It has made research easier.

⮚ It is one of the major handheld sources of entertainment of users at present.

⮚ Nowadays, Business processes are easily available through secured mobile  connections.

⮚ It is portable.

⮚ It supports cloud computing.

⮚ It provides remote access to the organizational data from any location.

⮚ It is an independent platform. It can be accessed from any hardware or software.


Disadvantages of Mobile Technology

⮚ Mobile technology requires faster and quality or GPRS or 3G or 4G connectivity.

⮚ It has security concerns; most wireless connectivity is unsafe.

⮚ Large power consumption is due to the use of batteries continuously and they do  not tend to last long.

⮚ The danger of misrepresentation i.e., credential

⮚ Extensive use of mobile devices results in health problems.


Internet of Things (IoT)

Internet of things (IoT) is the network of physical devices, vehicles, home appliances, and  other items embedded with electronics, software, sensors, actuators, and connectivity,  which enables these things to connect, collect and exchange data.

The Internet of Things (IoT) is a system of interrelated computing devices, mechanical and  digital machines, objects, animals, or people that are provided with unique identifiers  (UIDs) and the ability to transfer data over a network without requiring human-to-human  or human to-computer interaction.

By combining these connected devices with automated systems, it is possible to “gather information, analyse it and create an action” to help someone with a particular task or  learn from a process. A thing in the internet of things can be a person with a heart monitor  implant, an animal with a biochip transponder, an automobile that has built-in sensors to  alert the driver when tire pressure is low, or any other natural or man-made object that  can be assigned an Internet Protocol (IP) address and can transfer data over a network.

Advantages of IoT:

⮚ It automates tasks and helps to improve the quality of a business’s services and  reduces.

⮚ It helps to operate the business operations more efficiently, better understand  customers to deliver enhanced customer service.

⮚ It supports to improve decision-making and increases the value of the business.

⮚ It has the ability to access information from anywhere at any time on any device.

⮚ It provides improved communication between connected electronic devices.

⮚ Transferring data packets over a connected network saves time, effort, and money.


Disadvantages of IoT:

⮚ As the number of connected devices increases and more information is shared  between devices, the chances of the system being attacked also increases.

⮚ Organizations may eventually have to deal with massive numbers (maybe even  millions) of IoT devices, and collecting and managing the data from all those devices  will be challenging.

⮚ If there’s a bug in the system, every connected device will likely become corrupted.

⮚ Since there’s no international standard of compatibility for IoT, it’s difficult for  devices from different manufacturers to communicate with each other.



e-Learning applies to a learning/teaching or understanding about a topic with the help of  Information and Communication Technology. e-Learning allows us to learn anywhere and  usually at any time, as long as we have a properly configured computer, networks, devices,  etc. e-Learning can be CD ROM-based, Network-based, Intranet-based, or Internet-based.

It can include text, video, audio, animation, and virtual environments. It can be a very rich  learning experience that can even go beyond the lecture-based crowded classroom. It’s a  self paced, hands-on learning experience. The quality of the electronic-based training, as  in every form of training, is in its content and its delivery. However, e-learning can suffer  from many of the same pitfalls (drawbacks) as classroom training, such as boring slides,  monotonous speech, and little opportunity for interaction. The beauty of e-learning is that  new software that allows the creation of very effective learning environments that can  overcome the classic material being used in traditional learning. For example,  http://www.howstuffworks.com/

The concept of e-learning has become more popular throughout the globe because of the  Covid 19 pandemic. The tools like Zoom, Microsoft Teams, Cisco Webex Meetings, Google  Meet are also used for learning purposes.



m-Commerce (mobile commerce) is the buying and selling of goods and services through  wireless technology i.e., handheld devices such as cellular telephones and personal digital  assistants (PDAs).

Industries affected by m-commerce include:

⮚ Financial services, including mobile banking (when customers use their handheld  devices to access their accounts and pay their bills), as well as brokerage services (in  which stock quotes can be displayed and trading conducted from the same handheld  device).

⮚ Telecommunications, in which service changes, bill payment, and account reviews  can all be conducted from the same handheld device.

⮚ Service/retail as consumers is given the ability to place and pay for orders on the fly.

⮚ Information services, which include the delivery of entertainment, financial news,  sports figures, and traffic updates to a single mobile device.


 Social Media

Social Media is a computer-based technology that is used for the creation and sharing of  information, ideas, interests, and other forms of expression via virtual communities and  networks. Facebook, Twitter, YouTube are popular social media tools.


Advantages of Social Media:

⮚ It provides easier and faster way to communicate.

⮚ It provides worldwide real-time sharing of news and educational content.

⮚ It is one of the effective marketing/advertising tools at present.

⮚ It is the major source of entertainment at present.

⮚ It helps to understand better the latest trends and events.


Disadvantages of Social Media:

⮚ It has increased cyber-crime.

⮚ Productive times is lost due to time waster in social media.

⮚ It is a common tool at present for spreading rumours and fake news/updates.

⮚ It has a high risk of fraud.

⮚ It has decreased privacy.


Software Project Concept


The program is a sequence of instructions. It is the set or collection of instructions.


An instruction is a command given to the computer to perform a certain specified operation on given  data.


A set of programs written for a computer to perform a particular task is called software or the logical  components or set of procedures to routines or instructions are called software is the interface between  the computer and the user. It is a group of commands that tells the computer what to do and how to do  it.


A project is a well-defined task, which is a collection of several operations done in order to achieve a goal  (for example, software development and delivery).

Software Project Concept:

A software project is the complete procedure of software development from requirement identification  to testing and maintenance, carried out according to the execution methodologies, in a specified period  of time and budget in order to achieve intended software product.

Software Development Process

⮚ Software development process defines a sequence of tasks that must be carried out to build new software.

⮚ It groups the development activities into a sequence of phases.

⮚ A phase in sequence can only commence on the previous phase has been completed.

⮚ A report is produced at the end of each phase, describing what has been achieved and outlining  the plan for the next phase.

Fundamental activities for the software development process are

  1. Software Specification: The functionality or software and constraints on its operations must defined.
  2. Software design and implementation: The software to meet the specifications must produce.
  3. Software validation: The software must be validated to ensure that it does what the customer wants.
  4. Software evolution: The software must evolve to meet changing customer needs.

System Development Life Cycle (SDLC)


System is a set of interacting or interdependent components forming an integrated whole. A system can  be described as a set of objects joined together for a common objective.


It is the process of step by step changing or growing of any program and system.

Information System:

Information system is a system which processes supplied/collected data and generates information that  can be used for decision making at different levels.



SDLC (Software/System Development Life Cycle) is an organized way to develop a software/system.  System Development Phase or System Development Life Cycle or Software Development Life Cycle (SDLC)  is a methodology used to develop, maintain, and replace software/information systems.

⮚ It is a systematic process of developing any software. It helps in establishing a system, or software  or project, or plan. It gives an overall list of processes and sub-processes required for developing a  system.

⮚ SDLC consists of a set of development activities that have a prescribed order. It is the development  of software in chronological order.

System Development Life Cycle (SDLC), which is also known as Application Development Life Cycle, is a  term used in system that describes the process of planning, creating, testing and deploying an information  system.

Importance and the necessity of SDLC

  1. It helps to determine the needs of the user.
  2. It supports constant communication between the developer and the user.
  3. SDLC helps for easy identification of missing requirements.
  4. It ensures that the software meets the needs of its users.
  5. It supports proper analysis and design of the software.
  6. It ensures proper development and testing.
  7. Proper documentation support for future upgrade and maintenance.
  8. It provides flexibility for adding features even after the software is developed.


SDLC Phases

The different phases of SDLC are as follows:

  1. System Study or Preliminary Investigation and Feasibility study.
  2. System analysis or Determination of system requirements.
  3. System design.
  4. System development or development of software.
  5. System Testing.
  6. System Implementation.
  7. System Maintenance and Reviews or Evaluation.

  1. System study:

A system is intended to meet the needs of an organization. Thus the first step in the design is to specify these needs or requirements. The top manager of the organization takes the basic decision to use a computer based (information) system for managing the organization.

During this phase, the development team focuses on completing three tasks:

– Survey the system by collecting the inputs from various sources.

– Analyzing the current system (manual or automated) in depth and developing possible solutions to the problem.

– Selecting to the best solution and defining its function with a feasibility study.

  1. System analysis:

System analysis is the dissection of a system into its component pieces to study how those  component pieces interact and work.

⮚ System analysis is a term that collectively describes the early phases of development.

⮚ It is defined as those phases and activities that focus on the business problem, independent  of technology.

In this stage, the development team once again goes to the organization and studies very minutely  to collect all the drawbacks and details of information from the users, management and data  processing personnel.

Then the system analyst analyzes the information and proposes the following specifications.

  1.  Goals and objectives of the proposed system.
  2. Fundamental actions that must take place in the software.
  3.  Outputs to be produced.
  4. Inputs to be used.
  5. Processes to be performed.
  6. Interfaces to be provided.
  7.  Performance requirements to be met.
  8.  Organizational and other constraints’ to be met.


Feasibility study:

Feasibility study is the most important activity in the system analysis phase. It analyses the  proposed system from different aspects so that it makes us clear that how practical or beneficial  the system will be to the organization. So it tells us whether the system is feasible to design nor  not.

Need of feasibility study

⮚  It determines whether the system meets the goal of the clients or not.

⮚  It determines the strength and limitations before starting to develop the system.

⮚  It focuses on the boundary of the system’s outline.

⮚  It suggests new opportunities through the investigations process.

⮚  It provide quality information for decision making.

⮚  To provide documentation of the investigated system.

The different levels of feasibility study are as:

1) Economic feasibility: it concerns with cost effectiveness of the system. The main objective of  economic feasibility is to calculate approximate cost-both the development cost and the  operational cost and the benefits from the system.

2) Technical feasibility: it concerns with the availability of the hardware, software and the  support equipment for the complete development of the system.

3) Operational feasibility: it concerns with smooth operation of the system. It is all about the  problems that may occur during operation of the system after its development.

 4) Behavior feasibility: it concerns with behavior of the users and the society towards the new  system. Generally, most of the traditional employees are not easily ready to upgrade them  with the new system.

5) Social Feasibility: It is a determination of whether a proposed system will be acceptable to the  people or not.

6) Management Feasibility: It is a determination of whether a proposed system will be  acceptable to management or not.

7) Schedule(Time) feasibility: it is the process of splitting project into tasks and estimate time  and resources required to complete each task. It determines the deadline to complete a  system and schedule the task accordingly.

8) Legal feasibility: it concerns with legal issue of the system. If the system is illegal then the  system designing is meaningless. Everything is measured whether it is legal or illegal. It  considers copyright law, foreign law, foreign trade, tax, etc.


System design:

The next step is to develop the logical design of the system. During this phase, the logic of the  system, namely, the information requirement of users, and use this to find the necessary  database.

System design is concerned with the design of new system. It involves designing of various things  such as output design, input design, files design, processing and general program design etc.

Logical Design: Theoretically designing of the system is called logical design. The system could be  designed on the basis of the requirements.

Physical Design: The conversion of logical design into designing tools and techniques is called  physical design. It is more detail and complex jobs describing the solution of the problem. It uses  algorithms, flowcharts, pseudo codes, decision table, decision tree, E-R diagram, Data flow  diagram etc.

Theoretically designing of the system is called logical design. The system could be designed on the  basis of the requirements.

The conversion of logical design into designing tools and techniques is called physical design. It is  more detail and complex jobs describing the solution of the problem.

To create the logical design different kinds of tools are used.

⮚ Algorithm                     ⮚ Decision Table

⮚ Flowchart                     ⮚ Decision Tree

⮚ Pseudo codes               ⮚ Data flow diagram

⮚ Structured English         ⮚ E-R diagram

  1. System development: after designing a logical diagram of a system then next step is to convert into program. This process is called system development. Flowchart, algorithm, Pseudo code, etc. are the outlines the procedures for taking the input data and processing it into usable output.
  2. System testing: it is an investigation conducted to provide stakeholders with information about the quality of the product or service under test. System testing also provides an objective, independent view of the software to allow the business to appreciate and understand the risks of  software implementation.
  3. Implementation: implementation involves testing the installed system, converting from the old system to the new one and training the users. This phase consists of implementation of the system into a production environment, and resolution of the problem identified in testing phase.
  4. Maintenance and review: it begins after the system is implemented. Like any system, there is an ageing process that requires periodic maintenance of hardware and software. The content of the review will include objectives met, cost, performance, standards and recommendation.


System Analyst:

System analyst is person who is involved in analyzing, designing, implementing and evaluating computer based information systems to support the decision making activities and operations of an organization.

A good system analyst is:

  1. Understanding and commitment to the organization
  2. People skills
  3. Conceptual skills and
  4. Technical skills

A system analyst is information specialist. To be a system analyst, one must be knowledgeable  about the technical aspects of analyzing, designing and implementing computer-based systems.

A system analyst is a person who conducts a study, identifies activities and objectives and  determines a procedure to achieve the objectives.

Designing and implementing systems to suit organizational needs are the functions of the systems analyst.  One plays a major role in seeing the business benefits from computer technology.  An analyst is a person with unique skills. One uses these skills to coordinate the efforts of different types  of persons in an organization to achieve business goals.

The characteristics (attributes) of system analyst are as follows:

  1. Knowledge of organization.
  2. Technical Knowledge.
  3. Interpersonal Communication Skill.
  4. Character and Ethics.
  5. Problem-Solving Skill.

               ➔ Defining the problem

               ➔ Analyzing the problem

               ➔ Evaluating many alternatives

              ➔ Choosing the best alternatives

              ➔ System analysis and Design skills

The roles of system analyst area as follows:

  1. Change event
  2. Investigator and event
  3. Architect
  4. Psychologist
  5. Motivator
  6. Intermediary and diplomat

Duties and Responsibilities of System Analyst

  1. Defining Requirements
  2. Prioritizing Requirements
  3. Analysis and Evaluation
  4. Solving Problems
  5. Drawing up functional specification
  6. Designing System
  7. Evaluating System


SDLC (System Development Life Cycle):

Describes in Details:

  1. System study or Preliminary Investigation :

In this stage, the development team studies the present and identifies the drawbacks. They  interact with the users and gathers information from different sources to recognize the problems  of present system.


  1. System Analysis:

In this stage, the development team once again goes to the organization and studies very  minutely to collect all the drawbacks and details of information from the users, management  and data processing personnel.

Then the system analyst analyzes the information and proposes the following specifications.

  1.  Goals and objectives of the proposed system.
  2. Fundamental actions that must take place in the software.
  3. Outputs to be produced.
  4. Inputs to be used.
  5. Processes to be performed.
  6. Interfaces to be provided.
  7.  Performance requirements to be met.
  8. Organizational and other constraints’ to be met.


  1. Feasibility study:

Feasibility study is the most important activity in the system analysis phase. It analyses the proposed  system from different aspects so that it makes us clear that how practical or beneficial the system will  be to the organization. So it tells us whether the system is feasible to design nor not. Thus it is  necessary before system design.

The different levels of feasibility study are as:

  1. Economic feasibility: it concerns with cost effectiveness of the system. The main objective of economic feasibility is to calculate approximate cost-both the development cost and the operational cost and the benefits from the system.
  2. Technical feasibility: it concerns with the availability of the hardware, software and the support equipment for the complete development of the system.
  3. Operational feasibility: it concerns with smooth operation of the system. It is all about the problems that may occur during operation of the system after its development.
  4. Behavior feasibility: it concerns with behavior of the users and the society towards the new system. Generally, most of the traditional employees are not easily ready to upgrade them with the new system.
  5. Schedule feasibility: it is the process of splitting project into tasks and estimate time and resources required to complete each task. It determines the deadline to complete a system and schedule the task accordingly.
  6. Legal feasibility: it concerns with legal issue of the system. If the system is illegal then the system designing is meaningless. Everything is measured whether it is legal or illegal. It considers copyright law, foreign law, foreign trade, tax, etc.


  1. System Design:

System design is concerned with the design of new system. It involves designing of various things  such as output design, input design, files design, processing and general program design etc. This  state consists of logical design and physical design of the system.

      a. Logical Design: Theoretically designing of the system is called logical design. The system could be designed on the basis of the requirements.

      b. Physical Design: The conversion of logical design into designing tools and techniques is called physical design. It is more detail and complex jobs describing the solution of the problem. It uses algorithms, flowcharts, pseudo codes, decision table, decision  tree, E-R diagram, Data flow diagram etc.


System Design Tools:

The tools which are used to design the system in known as system design tools. They are used during  system analysis and design phase of the system development

        a. Algorithm: An algorithm is defined as the finite sequences of instructions for solving a problem

        b. Flowchart: A flowchart is the pictorial representation of an algorithm which is classified into two types’ system flowchart and program flowchart. The different symbols used in system flowchart are defined below:

             I) System flowchart:

System flowchart describes the internal architecture of a system that describes how data are  moved inside the internal components of a system.

           II) Program flowchart:

Program flowchart describes to solve the application types of real world problem.

       c. DFD (Data flow diagram):

DFD is the logical diagram to describe the flow of data inside the components of system. It is easier  to understand or grasp when being explained and most important to all, it is much more precise  and less ambiguous than a narrative one. The main components are: process, data store, data  flow, external entities.

    d. Context Diagram:

It is combination of many other DFD. It is the highest level of DFD. It contains only one process, representing the entire system, the process is given the symbol circle. The external entities are denoted by rectangle. The flow of data is described by arrow.

   e. ER (Entity Relationship) diagram:

The E-R diagram is an overall logical structure of a database that can be expressed graphically. It  was developed to facilitated database design and the simplicity and pictorial clarity of this  diagramming technique have done great help in the designing part of database. The main  components are attributes, entities and relationship.

    The diagrammatic representation of entities attributes and their relationship is described by E-R  diagram.



E-R diagram

     f. Case diagram:

Computer aided software engineering tool is automatic computer based program that helps for  software engineering and SDLC process. It is very fast and effective tools for the development of  big scale software. It helps in analysis, design, implementation, testing and maintenance.

    g. UML:

Unified Modeling Language is a standardized general purpose modeling language in the field of  object-oriented software engineering. The standard is managed, and was created by, the object  management group. UML includes a set of graphic notation techniques to create visual models of  object-oriented software.

   h. Decision Table:

A table allows us to identify the exact course of actions for given conditions in tabular form.  Decision table is a tabular representation of the logic of a decision, which specifies the possible  conditions for the decision and the resulting actions.

Parts of Decision Table.

     i. Decision Tree:

Decision tree is also a technique to represent condition and actions in a diagrammatic form in  computer. A decision tree allows us to identify the exact course of actions for given conditions in  tree structures.

    j. Pseudo Code:

It is a kind algorithm for solving a problem and the instructions of pseudo code are written by  using English phrase and mathematical expressions.


         5. System Development:

Programmers begin to develop the program by using a suitable High Level Language. In System  developments following processes are done.

  1.  Convert logical structure in to programs in programming language.
  2. Database is created.
  3.  User operational documents are written.
  4. Users are trained.
  5. The internal documentation of a system is prepared.


  1. System testing:

It is an investigation conducted to provide stakeholders with information about the quality of the  product or service under test. System testing also provides an objective, independent view of the  software to allow the business to appreciate and understand the risks of software  implementation.

  1. 1. White box testing: white box testing of software is predicted on close examination of procedural Logical path through the software and collaborations between components are tested by providing test case that exercises specific sets of conditions or loops. It is used when the tester  has access it the internal data structures and algorithms including the code that implement these.
  2. Black box testing: black box testing treats the software as a black box without any knowledge of internal implementation. Black box testing methods include: equivalence partitioning, boundary value analysis, specification based testing, etc. it is also called functional testing because it tests whether a system is functioning or not.


  1. Implementation:

Implementation involves testing the installed system, converting from the old system to the new  one and training the users. This phase consists of implementation of the system into a production  environment, and resolution of the problem identified in testing phase.

Types of Implementation:

  1. Direct Conversion: All users stop using old system at the same time and then begin using the new. This option is very fast, less costly but more risky.
  2. Parallel conversion: Users continue to use old system while an increasing amount of data is processed through the new system. Both the systems operate at the same time until the new system works smoothly. This option is costly but safe approach.
  3. Phased conversion: Users start using the new system component by component. This option works only for systems that can be compartmentalized. This option is safe and conservative approach.
  4. Pilot conversion: Personnel in a single pilot-site use the new system, and then the entire organization makes the switch. Although this option may take more time, it is very useful in big organizations where a large number of people make the conversion.


  1. Maintenance and review:

It begins after the system is implemented. Like any system, there is an ageing process that requires  periodic maintenance of hardware and software. The content of the review will include objectives  met, cost, performance, standards and recommendation.

Types of Maintenance

  1. Corrective Maintenance: it corrects the run time errors during the operation.
  2. Adaptive Maintenance: It modifies or adds new features in the system.
  3. Perfective Maintenance: It makes the system perfect, up-to-date and improve the life of the system.


System Development Model:

During software development or system development for organizations, a common process framework  is established, defining a small number of framework activities that are applicable to all software projects,  regardless of their size complexity. For a better paradigm of a software process, several models are  designed and implemented. It is the choice of system analyst which model is used to achieve the goal.  The different models are:

  1. Waterfall model:

Waterfall model is a systematic and sequential model to develop software that begins with  requirements analysis to operation and maintenance. It describes a development method that is  linear and sequential. It is an oldest type of model for software engineering. The fundamental  processes of waterfall model are as follows:

  1. Requirements analysis and definition: it is the first stage of waterfall model. In this stage, the developer should identify the actual requirements of the given problem.
  2. System design: in this stage the systems design process partition the requirements to either hardware or software systems.
  3. System Development: During this stage, the system design is converting into development.
  4. Integration and system Testing: The individual program units or programs are integrated and tested as a complete system to ensure that the software requirements have been met.
  5. Operation and maintenance: in this stage, the system is installed to the desire location. The maintenance involves correcting errors which were not discovered in earlier stages of the life cycle, improving the implementation of system units and enhancing the system’s service as  new requirements are discovered.


  1. It is simple model suitable for small size project.
  2. It is less expensive.


  1. It has no back track mechanism.
  2. It is not suitable for large size project.
  3. It has lack of proper documentation.
  1. Prototyping model:

It is the iterative process of system development which is more appropriate for developing new  system where there is no clear idea of requirements, inputs and outputs. These systems are then  continuously modified until the user is satisfied.

  1. Identify the user needs: the system analyst interviews the user to obtain an idea of what is required from the system.
  2. Develop a prototype: the system analyst, working uses one or more prototyping tools to develop a prototype.
  3. Determine if prototype is acceptable: the analyst educates the user in prototype use and provides an opportunity from becoming familiar with the system.
  4. Use the prototype: the prototype becomes the operational system.


  1. The users get a better understanding of the system being developed.
  2. Errors can be detected much earlier as the system is made side by side.
  3. Quicker user feedback is an available leading to better solutions of the system.


  1. It leads to implementing and repairing way of building systems.
  2. It may increase the complexity of the system as scope of the system may expand beyond original plans.
  1. Spiral system:

In this model, process is represented as a spiral rather than as a sequence of activities with  backtracking. It is a software development process combining the elements of both waterfall and  prototyping model. The spiral model is intended for large, expensive and complicated projects. This is the most realistic model because it uses multidimensional approach for software  development. The activities in SDLC are organized in a spiral structure that has many cycles which  starts from the center of the spiral and goes out as it program and becomes matured. Each of the  complete spiral segment is divided into four different attributes knows as:

  1. Planning: the project is reviewed and a decision made whether to continue with a further loop of the spiral. If it is decided to continue, plans are drawn up for the next phase of the project.
  2. Risk analysis: for each of the identified project risks, a detailed analysis is carried out. Steps are taken to reduce the risk. For example, if there is a risk that the requirements are inappropriate, a prototype system may be developed.
  3. Software development (Engineering): after risk evaluation, a development model for the system is chosen.
  4. User evaluation: specific objectives for the phase of the project are defined by the evaluation of users. Constraints on the process and the product are identified. And a detailed management plan is drawn up.


  1. It emphasizes quality.
  2. It is effective for regular updating the system.
  3. It emphasizes risk reduction techniques.


  1. Full scale risk analysis requires training, skill so it may appropriate only for large  projects.
  2. This model is relatively untested.


  1. Agile Software Development:


It is a software development method based on iterative and incremental development in which  requirement and solutions evolve through collaboration between self-organizing, cross functional  teams.



Documentation is the process of collecting, organizing, storing and maintaining a complete record of  system and other documents used or prepared during the different phases of the life cycle of the system. It consists of the detail description about software requirements specification, feasibility report, and  software designing report, description about input-output and processing mechanism, source code,  comments, manuals, guides and effective help desk.

Types of Documentation

  1. Internal Documentation: It is used by the system analyst and the programmer during development process. It is very useful for the development period and also useful in future for the modification and maintenance for the software.
  2. External Documentation: It is used by the user during the running time of the software. It includes the detail description in terms of manuals, guide and help files. It is mainly deals with how to effective use of software.


  1. What are the programming methods or approaches of program development?

There are two approaches of program development. They are Procedure Oriented Programming and Object-Oriented Programming. Procedure Oriented Programming is a conventional method of programming and the Object-Oriented Programming is a modern or latest programming method.

  1. What is Procedure Oriented Programming?

It is a conventional or old method of programming, in which the program is written into many small parts  and combined together. In this approach, the functions are created and the data is not very crucial.  Variables are created for the data handling and they are treated as the global and local variables. Creation  of the variables inside of the sub programs is known as local variable and the creation of the variables in  the main module is called the global variable. Global variables can be accessed from any modules but the  local variables can be accessed only within the local modules. The alteration of data is very high.

  1. What are the features of Procedure Oriented Programming?

The characteristics or features are as follow:

a) A large program is broken down into small programs or procedures.

b) It focuses on the functions rather than the data.

c) Variables are created as local and global.

d) The possibility of data alteration is very high, which is the main disadvantage of this approach.

e) It follows top down method.

  1. What is Object Oriented Programming?

It is a modern approach of programming. It is highly known as OOP in short form. In this method, all the  real world entities are treated as the objects and objects are collected in a class. Even the classes are  controlled by the Superclass. And by the inheritance feature, the changes on the superclass are easily  passed to its subclasses. Similarly, it was developed to overcome procedure oriented programming  method and the data is given high priority rather than the functions. Data can be hidden, so that the  possibility of data alteration is very less.

  1. What are the characteristics of OOP?

a) Emphasis is given to the data.

b) Program are divided into multiple objects.

c) Functions and data are tied together in a single unit.

d) Data can be hidden to prevent accidental alteration.

e) It follows the bottom up approach.

  1. What are the differences between Procedure Oriented and Object Oriented Programming?
Procedure Oriented Object Oriented
1. Emphasis is given to procedures. 1. Emphasis is given to data.
2. Programs are divided into multiple modules. 2. Programs are divided into multiple objects.
3. It follows top-down method. 3. It follows bottom-up method.
4. Generally data cannot be hidden. 4. Data can be hidden.
5. It does not model the real world perfectly. 5. It models the real world perfectly.
6. Maintenance is difficult. 6. Maintenance is easy.
7. Code reusability is difficult. 7. Code reusability is easy.
8. Examples: FORTRAN, COBOL, Pascal, C, etc. 8. Examples: C++, JAVA, Smalltalk, etc.
  1. Write short notes on the following:

a) Object

All the entities of a program used in OOP method are called objects. Here entities represent a group of  people, teachers, students, books, cars, etc. Each entity or object does have an attribute called  characteristics and the behavior or functions. For example, a car can be an object. The colour like blue,  black, size, weight, etc. are the attributes or the characteristics, which distinguishes to it with other  objects and move, turn, etc. can be the functions.

b) Class

Class is a user defined data type in OOP, which defines the data types for all the objects, which run under  it. Or it collects the objects of its similar data types. For example, a class vehicle can have the objects like  car, bus, truck, etc. Similarly a class school can have students, teachers, staff, etc.

c) Abstraction

It is a feature of hiding internal detail of any object. It provides only the interface to the user, which makes  them easy to use but does not show the details of that object, how that works and how that is made. Due  to this feature, OOP has become very secure platform for its data from being accidental alteration.

d) Encapsulation

It is a process of combining the data and functions together. OOP gives more emphasis on the data rather  than the functions or procedures. Many functions can use the same data but the instruction given to the  function to use any particular data and combining them together is the encapsulation. Due to its unrelated  functions cannot use unnecessary data in the program.

e) Inheritance

Inheritance is the process of creating new classes based on the existing class. The new classes require the  features of the main class called the Super class and it is provided through the feature called Inheritance. By the Inheritance feature Super class can coordinate with its subclasses. It models the real world. It  allows the extension and reuse of existing code without having to rewrite for the new created classes.

f) Polymorphism

It is a feature of OOP, which refers to the way of operating the same operator in different ways and  different method or purpose. Operator overloading and the operation overloading are the examples or  Polymorphism. For example ‘+’ operator can be used for arithmetic operation and string concatenation  both. This facility or feature is an example of Polymorphism. It reduces the number or keywords or  operators.

  1. What are the advantages and disadvantages of OOP?


a) Code repetition is reduced by the various techniques like inheritance.

b) Data is more secure due to the data hiding feature called abstraction.

c) Existing classes can serve as library class for further enhancements.

d) Division of a program into multiple objects makes the software development easier. e) Software complexity is less.

f) Upgrading and maintenance of software is easy.

g) It perfectly models the real world system.

h) Code reusability is much easier than the conventional programming system.


a) Compiler and runtime overhead is high.

b) Software developer should analyze the problem in object oriented way.

c) Requires the mastery in software engineering and programming methodology.

d) Useful only for the large and complex projects.


Application of OOP

  1. Expert System
  2. Artificial intelligence
  3. Management information systems.
  4. Decision support system.
  5. Computer based training and education
  6. Object- oriented database.
  7. Computer games.
  8. Mobile applications.
  9. Internet based applications.
  10. Designing user interface for software.
  11. Security System


What is C? Explain its development process.

C is a high level language because no need for any architecture knowledge in normal English form. C is a compiler because it can translate the whole program at a time so we can call compiler. C is structured  programming language. It is called also procedural oriented programming language, function oriented  language, module programming language. It is simple, reliable and easy to use.

What are the features of C? What are its advantages and disadvantages?

C is a computer language and a programming tool which has grown popular because programmers  preferred it. It is a tricky language but a masterful one.

The C programming languages has the following features:

  1. It has small size.
  2. It has extensive use of function call.
  3. It is a strong structural language having powerful data definition methods.
  4. It has low level (Bitwise) programming available.
  5. It can handle low level activities.
  6. Pointer makes it very strong for memory manipulations.
  7. It has level constructors.
  8. It can produce efficient programs.
  9. It can be compiled on variety of computers.

Advantage of C language:

⮚  It is machine independent programming language.

⮚  It is easy to learn and implement C language.

⮚  It can be implemented from mobile device to mainframe computers.

⮚  It is the mother of all modern programming language.

Disadvantage of C Language:

⮚  There is no runtime checking.

⮚  It has poor error detection systems.

⮚  On large programs, it is hard to fix errors.

⮚  It does not support modern programming methodologies oriented programming language.

What is preprocessor? Explain with its types.

The compiler of C has a preprocessor built into it. Lines that begin with # are called pre-processor  directives. Each C program must start with proper header files (i.e.<stdio.h>) starting with ‘#’, sign, ‘include’  and a header file name enclosed within triangle brackets.

What is header file? List the header files with some functions, where are they used?

A file that is defined to be included at the beginning of a program in C language that contains the  definitions of data types and declarations of variables used by the functions in the program is called header  file.

  1. Header files commonly contain forward declarations of classes, subroutines, variables, and other identifiers.
  2. The header file in c is called standard library functions.
  3. The entire header file has the extension .h
  4. A header file is used to define constants, variables, macros and functions that may be common to several applications.
  5. The updating and reading data of any function can be performed by using the header files.

Some of the frequent used header files are explain below:

S.N. Header File Description Main Functions
1. stdio.h Standard input and output fpen(), fclose(), rename(), gets(), puts(),  getchar(), scanf(), printf() etc.
2. conio.h Old MS-DOS compiler header file,  used for console input & output. getch(), getche()
3. math.h Mathematical calculation in C  program. sin(x), cos(x), log(x), pow(x,2), sqrt(x),  cbrt(x), ceil(x), floor(x) etc.
4. complex.h Complex arithmetic cpow(x,p), csqrt(x), ctan(x), ctanh(x),  cabs(x)
5. string.h String / Words manipulation  function strlen(y), strcpy(z,y), strcmp(z,y),  strcat(z,y), strupr(y), strlwr(y) etc.
6. ctype.h Character manipulation type  header file toupper(y), tolower(y), isupr(y), isspace(),

isalnu(y), toascii(y) etc.

7. stdlib.h General purpose standard  library. rand(), malloc(), calloc(), abort(), exit()  abs(), free() etc.

Fundamentals of C

  1.  What are the character set used in C?

A group of alphabetic, numeric and other characters that have some relationship with C programming  language and recognized by compiler is called Character set. A character set can also contain additional  characters with other code values.

The keywords, identifiers and other variables are constructed by using character set. The character set  consists of following elements.


   2. Define the term identifier, keywords and Tokens.

Identifiers:- Identifiers can be defined as the name of the variables, functions, arrays, structures etc  created by the programmer. They are the fundamentals requirement of any language. The identifiers  are defined according to the following rules:

⮚  Identifiers consists letters and digits.

⮚  First character must be an alphabet or underscore.

⮚  Uppercase and lowercase are allowed but not same, i.e. Text not same as text.

⮚  Only one special character underscores (_) will used.

For example, int a_b; Where a and _b are valid identifiers.

Keywords:-Keywords are the reserved words which have standard, predefined meaning in C language. Keywords  cannot be used as names for the variables or other user defined program elements. There are 32 keywords  available in C.

Common examples are as follows.


In a C source code, the basic element recognized by the compiler is known as tokens. A token is source program text that the compiler does not break down into components elements.

⮚  The keywords like int, float, if, for etc.

⮚  Identifiers like main, printf, void etc.

⮚  Constants like a,b,c etc.

⮚  String literals like name, address, phone etc.,and

⮚  Operators like &&, ! etc.

⮚  Punctuation characters such as [ , ] , { , } , ( , ) , ; , : are also tokens.

3. Explain data types used in programming with examples.

Data types:

It is the set of keywords to declare variables. A set of data that specifies the possible range of values in a  program and stored in memory are called data types. Data types are used to define variables before use it.

Types of data types in C

1) Primary data types

2) Secondary data types

Primary Data Types: The basic fundamental of data having unit feature on C programming is called Primary  Data Type.

Example :

Data Type Type Memory Require

Format Specifies

Char Character 1 byte % C
Int Integer 4/2 byte %d
Float Floating point number 4 byte %f
Long Floating number 4 byte %ld
Double Large floating point number 8 byte %lf
long double Very large floating number 12 byte %lf



Variable are simply names that can change the value while executing a program. It allocates memory  space inside a memory of computer. A variable can have only one value assigned to it in every time of  execution of the program. Its value can change in different executions.

✔  They must always begin with a letter, although some systems permit underscore as the first  character.

✔  White space is not allowed.

✔  A variable should not be a keyword.

✔  It should not contain any special characters.

Types of variable 

  1. Numeric Variable: The variable that store numeric data only is called numeric variable. The numeric data may be whole number or fractional number. Examples are integer, floating point and double.
  2. String Variable: The variable that stores character data only is called string variable. The string data may be single character or string. Examples are character, array of character (string), table of string.

Constant variable: 

A constant is fixed entity. It does not change its value during the entire program execution. Constants can  be classified as:

  1. Integer constants
  2. Floating point constants
  3. Characters constants
  4. String constants
  5. Symbolic constants
  6. Escape sequence constants



The input and output data are formatted by specific pattern. These Patterns are generated by using specific tokens in C programs. These tokens used to format data are called specifier. Most of the specifier used by printf and scanf functions. Types of mostly used specifier are explained below.

Escape Sequence: They are a type of specifier. These non printable characters are used to format text on the output screen. These escape sequence character are place after backslash \.

Escape sequence Name Meaning
\’ Single quote It prints ‘ in output
\” Double quote It prints ” in output
\n New line It creates new line in output display
\t Tab It creates tab or 8 spaces in place of \t


❖  Format Specifier: The output and input data are display and receive in specific pattern. Format  specifier uses the token % and character(s) after it. It is used to format for all types of data i.e.  integer, float, character and string.

Format Specifier Used by scanf() function
%d , % i Signed integer + or – number o to 9
%f Scans floating point numbers.
%s String, Collection of character i.e. word
%c Character, one single key stroke.



An operator is a symbol that operates on a certain data type. The operator generally remains between the  two operands. An expression is a combination of variables, constants, and operators written according to  the syntax of the language. The data items that operators act upon are called operands.

Types of operator:

  1. Arithmetic Operator(Binary Operator)
  2. Relational Operator (Comparison Operator)
  3. Logical Operator (Boolean Operator)
  4. Assignment Operator
  5. Increment and Decrement Operators (Unary Operator)
  6. Conditional Operator (Ternary Operator)
  7. Bitwise Operator
  8. Comma Operator
  9. Size of Operator
  1. Arithmetic Operator

The arithmetic operators perform arithmetic operations and can be classified into unary and binary  arithmetic operations. The arithmetic operators can operate on any built-in data type. A list of arithmetic  operators and their meanings are given below:

Operator Meaning




additional or unary plus

subtraction or unary minus



modulo division (returns remainder after division)

  1. Relational Operator

The relational operators help to compare two similar quantities and depending on their relation, take some  decisions. If the condition is true, it evaluates to an integer 1 and zero if the condition is false. The basic  types of relational operator are:

Operator Meaning






less than

greater than

less than or equal to

greater than or equal to

equal to

not equal to

  1. Logical Operator

The logical operators are used to give logical value either true or false. They compare or evaluate logical  and relational expressions. There are three logical operators.

Operator Meaning Examples
&& Logical AND (a>b) && (a>c)
|| Logical OR (a>b) || (a>c)
! Logical NOT !(a==b)
  1. Increment and Decrement Operators:

The increment and decrement operators are very commonly used in C language. The increment operators  and decrement operators are extensively used in the loops using structures such as for, while, do, etc. The  syntax of the operators is given below:

++<variable name>

–<variable name>

<variable name>++

<variable name)–

Pre increment

Pre decrement

Post increment

Post decrement

The pre increment operator increases the value of the variable by 1 and then the processing does whereas  post increment first processes and increase the value of it by 1.

  1. Conditional Operator:

A conditional operator is very rarely used. This can be carried out with the conditional operator (? : ) An  expression that makes use of the conditional operator is called a conditional expression. This can replace  the if-else statement. The syntax of conditional operator is:

Expression_1 ? expression_2: expression_3

During evaluating the conditional expression, expression_1 is evaluated at the first step. If expression_1 is  true (nonzero), then expression_2 is evaluated and this becomes the value of the conditional expression.

Library function:

The special functions that are well defined in C programming languages are called library functions such as  printf(), scanf(),strlen(), sqrt(), tolower(), toupper(), getchar(), putchar() etc.

Control Structure:

Control structures are those programming constructs which control the flow of program statements  execution in a program. Types of Control Structure

i) Branching / Decision ( Selective Control Structure)

ii) Looping (Repetitive Control Structure)

iii) Jumping (Unconditional Control Structure)

  1. Decision (Selective) Control Structure

It is mainly used for decision making. It is also called conditional statements. Selection is made on  the basis of condition. We have options to go when the given condition is true or false. The flow of  program statements execution is totally directed by the result obtained from checking condition.  Types

a) Conditional Statements:

i. if statements:

It is used to execute an instruction or block of instructions only if a condition is fulfilled. Syntax,





E.g. Write a program to read a number and find even or odd by using if().



ii. if else statements:

If the condition is true then the if() portion statements are evaluated otherwise else part of the  statements are evaluated.


if( condition)


Block of statements;




Block of statements;


E.g. Write a program to input any two numbers and display the largest one.



iii. if() else if() statements

When we have two or more condition to be checked in a series we can use if else if statement. It is  also known as multiple conditional statement or multipath conditional statement /if else ladder. Syntax,

e.g. Write a program to find the largest number among three input number .



iv. Nested if else statements

An entire if else statement written within the body of if part or else part of another if else statement is  called nested if else statement. It is used when a condition is to be checked inside another condition at a  time in the same program to make decision.


E.g. Write a program that reads marks of five subject and calculate total mark and percentage. Also awards the division on the basis of following criteria.

Percentage                                                                      division 

p>=75                                                                              distinction 

p>=60 and <75                                                             first 

p>=45 and <60                                                          second 

p>=35 and <45                                                         third 

otherwise                                                                  failed



b) Switch case statements:

The switch statement can be used instead of multiple if() else conditional statements. The switch  control statement is mainly used to generate menu based programs.

Switch(expression 1)
    Case condition 1 : Statements ….break;
            .Case condition n –
        1 : Statements…….break;
    statement n;

E.g. Write a program which reads any two integer values from the user and calculates sum, difference and  product using switch case statements.



  1. Looping Statement

The looping statement is also called repetitive or iterative control structure. Looping statements are the  conditional control flow statements that repeats a certain portion of the program either a specified  number of times or until a particular condition is satisfied or true.

Types of loop

i) For Loop

ii) While Loop

ii) Do while Loop

i. For Loop:-

The execution of for loop until the condition is true. The for loop is a entry control loop because it  checks the condition at entry point. 


  1. Write a program to print the natural number from 1 to 10.



2. Write a program to display even numbers from 1 to 20 and display their sum also. 



3. Write a program to find out sum of the cubes of first 10 numbers.



Nested for loop:

When for loop is declared inside another for loop is called nested for loop. The life of the inner for loop  is depending over the outer for loop. If the outer for loop condition is true then inner for loop is  evaluated. And will executes all the statements until condition is true if the inner for loop to be false  then the outer for loop condition is reevaluated and so on.

For example:

  1. Display the following output :

10 20 30 40 50

10 20 30 40 50

10 20 30 40 50

10 20 30 40 50

10 20 30 40 50



2. Write a program to display following output:








While Loop:-

The while loop is also a entry control loop. While loop first checks whether the initial condition is  true or false and finding it to be true, it will enter the loop and execute the statement.


1. Write a program to print even number from 1 to 100.



Do while loop:- 

This loop is an exit control loop. This loop runs at least the once even though the termination  condition is set to false. This loop test the condition at exit point hence it is called exit control loop.  The syntax of the loop is similar to while loop.


1. Write a program to display odd numbers from 100 to 1.


2. Write a program to read the employee name, address for the N employee and display by  using while loops.


Difference between While loop and Do while loop:
S.N.  While loop  S.N.  Do while loop
It is an entry controlled loop.  It is an exit controlled loop.
Testing starting in top  Testing started at the bottom.
It has keyword while  It has the keywords do and while.
If the first condition is true then the statement is  executed otherwise no. But in case at least one time executed  statement if the condition is false.
Loop is not terminated with a semicolon.  Loop is terminated with a semicolon.

while (expression) 



6 Syntax,



} while (expression);


The jump Statements 

  1.  break statements 
  2.  continue statements 
  3. goto statements

1) break statements: 

 The break statement is used to terminate a loop or to exit from a switch. it can be used within a  for, while, do while switch statement. 



2) The continue Statement  :

It skips the remaining statements in the body a while, for or do ……while structure proceeds with  the next iteration of the loop. The continue statement is used to bypass the execution of the further  statements.



3) Go to statement: 

The goto statement is used to send the pointer to the specified label. If the label is not  defined then the goto statement will not work.



Some important C programs:

  1. Reverse order 
  2. Factorial number 
  3. Fibonacci series 
  4. Prime or composite number 
  5. Even or odd number 
  6. Palindrome or not. 
  7. Sum of individual digits 
  8. Armstrong number or not 
  9. Multiplication table 
  10. Find list of prime number  
  11. Display a perfect square number.

1. Write a program to input any value and display that value in reverse order.



2. Write a program to input a positive number and find its factorial number. 



3. Write a program to display the Fibonacci series. 1 1 2 3 5 8 13 …………………n.



4.Write a program to read a number and to check the number is prime or not.



5.Write a program to find out even numbers from 1 to 100 and find their sum also.



6.Write a program to input a number and find out if the number is palindrome or not.



7.Write a program to input a positive number and find out the sum of its individual digits.



8.Write a program to input a number and check if it is an Armstrong number or not.



9.Write a program to display the multiplication table of a given number. 



10.Write a program to display all prime numbers upto 1000. 



11.Write a program to display all perfect square numbers from 100 to 500.  



Arrays and String Function: 

Arrays :

An array is a collection of data of the similar type all of which are referred by a single variable  name. For example, instead of using 50 individual variables to store the names of 50 students, we can use an  array to store the names of 50 students. 

Advantage of arrays: 

  1. It is easier for handling similar types of data in a program. 
  2. It is efficient for solving problems like sorting, searching, indexing etc. 
  3. It is easier to solve matrix related problems. 
  4. Graphics manipulations can easily be done using arrays. 

Disadvantages of arrays:

  1. It is not possible to hold dissimilar types of data in an array. 
  2. It is difficult to visualize the multi dimensional array. 
  3. It is static in nature so it is difficult to define the size of the array during running

 There are two types :

  1. One/signal dimensional: The values on an array variable assigned in one row and more than one  column are called signal dimensional array. 

Syntax: type array_name[max. size]; 

Example int n[10]; 

int age[]= {18,12,19,20,16,16,17}; 

  1. Two/Double dimensional: Two dimensional arrays are capable of storing data in multiple row and  columns. 

Syntax: type array_name[No.Rows] [No.Cols]; 

Example int n[10][5];

int matrix[3][3]= {{0,1,2},{3,4,5},{6,7,8}};


Program: Write a program to read 50 students’ marks and display them. 



Program: Write a program to input 5 numbers with constant values initialization in array to display the  sum. 



Program: Write a program to input the age of 20 students and count the number of students having age  in between 20 to 25. 



Program: Write a program to find the largest number among ‘n’ numbers. 



Program: Write a program to read a matrix, store it in an array and display it. 



Program: Write a program to calculate the average age of 10 students. 



Program: Write a program to accept the age of 10 different employees and count the no. of employees.

i) Whose age is more than or equal to 60

ii) Whose age is less than 35



Program: Write a program to store N numbers in array and print out the sum with the entire array  variable. 



Program: Write a program to accept 10 different numbers in array and sort in descending order.



Program: Write a program to store twelve numbers in a double dimensional array and print out the values  in table with row wise addition.



Program: Write a program to enter elements for 2×2 matrix and display its transpose.


Program: Write a program to enter elements for 3×3 matrix and display its sum.



String Function: 

The strings are manipulated by specific string function. These are inbuilt functions and defined within  string.h header file. 

  1. strlen( ): It returns the number of character present in the string. 

                                   Syntax: strlen(string);

Program: Write a program to store string in array variable and find the length.


     2. strrev( ): It helps to reverse the character of the string. 

                                 Syntax: strrev(string); 

      3. strupr( ): It converts lowercase letters in string to uppercase.

                                Syntax: strupr(string); 

     4. strlwr( ): It converts uppercase letters in string to lowercase.

                              Syntax: strlwr(string); 

     5. strcpy( ): It is used to copy the content of one string to another. 

                              Syntax: strcpy(target,source); 

     6. strcat( ): It is used to concatenate source string to the target string.

                              Syntax: strcat(target,source); or strcat(source,target); 

     7. strcmp( ): It compares two strings on the following basis. 

                             Syntax: strcmp(string1,string2);

Program: Write a program to show use of trcpy,strrev,strupr and strlwr.


Program: Write a program to read two strings in an array and concatenate strings.


Program: Write a program to read two strings in an array and compare two strings and check that string is  palindrome or not.



Functions are the building block of statements, which take some data, manipulate them and can return a  value. Bug free functions can be used repeatedly from other parts of the program. There are two types of  functions:

  1. Library Functions (built in or ready made): C has the facilities to provide library functions for  performing some operation. These functions are present in the c library and they are predefined.  for eg. 
    1. scanf( ); 
    2. printf( ); 
    3. getchar( ); 
    4. putchar( ); 

2. User Defined functions (Defined by user according to need): users can create their own function  for performing this type of function called user defined function.

Syntax  of user defined functions;

  1. Write a program to calculate simple interest using function.


2. Write a program to calculate the area of a rectangle using function. 



  1. Big programs can be divided into smaller modules using functions. 2. Program development will be faster. 
  2. Program debugging will be easier and faster. 
  3. Use of functions reduces program complexity. 
  4. Program length can be reduced through code reusability. 6. Use of functions enhance program readability. 
  5. Several developers can work on a single project. 
  6. Functions are used to create your own header file i.e. mero.h 
  7. Functions can be independently tested.


With passing arguments 

Program: Write a program to find out the area of a circle through a given radius as an argument using a function.


Program: Write a program in C to create a function to pass two numbers as an argument and to return a  sum to the calling function. 



Without passing arguments 

Program: Write a program to find out the sum and square of two input number without passing arguments  function.



Recursive Function:  

The function which performs recursion is called a recursive function. Recursion is a process by which a  function calls itself repeatedly until some specified condition has been satisfied. 

The function which calls itself is known as recursive function and the concept of using recursive functions  to repeat the execution of statements as per the requirement is known as recursion. The criteria for  recursive functions are: 

  1. The function should call itself. 
  2. There should be a terminating condition so that function calling will not be for an infinite number of  times.

Program: Write a program to calculate factorials by using a recursion process. 



Program: Write a program to read a number and make the sum of individual digits & print using recursion  technique. 



Program: Write a program to calculate sum of n-natural numbers using recursion/recursive function.



Accessing a Function: 

There are two types of accessing a function. 

1. Call by value: Only the values of arguments are the same to the function and any change made to the  formal arguments does not change the actual arguments.

Program: Write a C program trying to exchange two values by using a call by value accessing function.


2. Call by reference: When we pass an address to a function the parameters receiving the address should  be pointers. The process of calling a function by using a pointer to pass the address of the variable is  known as call by reference.

Program: Write a C program to exchange two values by using call by reference accessing function.



Structure and Union 


Structure is a collection of variables under a single name. As an example, if we want to store data  with multiple data types like roll number, student name, address, phone number and class of a student  then C supports a structure which allows us to wrap one or more variables with different data types. Each  variable in a structure is called a structure member. To define a structure, we use the struct keyword. Syntax;

We can also declare a structure ,

We can also declare array of variables at a time of declaring a structure as: 


Unions like structure contain members whose individual data types may differ from one another.  However the members that compose a union all share the same storage area within the computer memory  where as each member within a structure is assigned its own unique storage area. Syntax;

Union union_name 

Union_member (s); 



Difference between Structure and Union:
S.N.  Structure  S.N.                                                     Union
1. Structure is designed by using the ‘struct’  keyword. 1.  Union is designed by using ‘union’ keyword.
2. Syntax: struct structure_name 


 Data_type member1; 

 Data_type member1; 


2.  Syntax: union union_name 


 Data_type member1; 

 Data_type member1; 


3.  All the members of the structure variable  can be processed at a given time. 3.  Only one member of the union variable can be  processed at a time because only one member  of the union variable can be active at a time.
4. We use structure variables if memory is  large and have to store values of all of the  variables. 4.  We use union variables if memory is less and  have to store one variable in one of the  declared variables or members.
5.  Structures are broadly used in  


5.  Unions are not used broadly as much as  structures.
6. Structure declaration takes a large amount  of spaces to store data and values. 6.  Union declaration shares the same area of  memory to save storage space.


Example 1: Write a C program to read different structure variables and display them.



Program: Write a program to input the employee name and their basic salary of n employees and display  the record in proper format. 



Program: Write a program that reads different names and addresses into the computer and rearrange the  names into alphabetical order using the structure variables.





A pointer is a variable that points to a memory location where data is stored. Each memory  cell in the computer has an address which can be used to access its location. A pointer variable points to a  memory location rather than a value.  

– We can access and change the contents of the memory location.  

– A pointer variable contains the memory location of another variable. 

– The asterisk tells the compiler that you are creating a pointer variable. 

The pointer declaration syntax is as shown below. 

Pointer_type *pointer_variable_name; 

For e.g. int *p;

Address (&) and indirection (*) operator 

The address (&) operator and immediately preceding variable returns the address of the variable  associated with it. Hence, the address of (&) operator returns the address of memory location in which the  variable is stored.  

The indirection (*) operator is used to extract value from the memory location stored in the  particular memory location whose address is stored in a pointer variable. 

The syntax of declaring address operator to pointer variable is as follows. 

Pointer_variable = &variable_name;  

For Example;

int *ptr, num=25; 

ptr = &num;

Program: Write a complete program to display address and value of the pointer variable.


Pointer to Arithmetic 



Write a C program to increment a pointer.



Assignment pointer value to function 

Program: Write a program to pass pointer variables to function sum them and display after returning it.



Array of pointers: 

Program: Write a C program to assign an array, place these arrays in a pointer variable and display array value  along with its address.



Pointer to Pointer 

Program: Write a program to demonstrate the use of pointer to pointers:



Advantage of Pointer 


Working with files 

Data file requires that information be written and stored on the memory device in the form  of a data file. Thus, data file access and alter that information whenever information in C.

Sequential and Random Access File 

Sequential Access File: 

The sequential access files allow reading the data from the file in one after another i.e. in sequence. There  is no predefined order for accessing data file. All the processes are declare and assigned by the compiler  during run time of the program.  

Random Access File:  

The random access files allow reading data from any location in the file. Sometimes, we need to read data  file from reverse, middle and from specific location. To achieve this, C defines a set of functions to  manipulate the position of the file. The inbuilt function fseek( ), lseek( ), rewind( ) and ftell( ) are the some  of the common examples of random access files.  

Opening, Reading, Writing and Appending on/from Data File: 

Once the file pointer has been declared, the next step is to open file. There is an inbuilt function to open a  file. The function fopen( ) is used to create a steam for use and links of new open file. This function return a  file pointer and takes two parameter one for name of file and other for mode for the file. The syntax is as  follows; 

FILE *f; 

f = fopen (“file_name.extension”, “mode_of_open”);

The modes of the data file are as follows:

S.N.  Mode  Description
“r” / “rt”  It opens a text file to read only mode.
“w” / “wt”  It creates a text file to write only mode.
“a” / “at”  It appends text to already data containing file.
“r+t”  It opens a text file for read and write mode.
“w+t”  It creates a text file for read and write mode.
“a+t”  It opens or creates a text file and read mode.
“rb”  It opens a binary file for read only mode.
“wb”  It creates a binary file for write only mode.
“ab”  It opens or create a binary file for append mode.
10  “r+b”  It opens a binary file for read and write mode.
11  “w+b”  It creates a binary file for read and write mode.
12  “a+b”  It opens or creates a binary file for append mode.



  1. fputc= Store character into the file. 
  2. fputs= Store string into the file. 
  3. fgetc= fetch character from the file. 
  4. fgets= fetch string from the file. 
  5. fwrite= store data (structure) into the file. 
  6. fread= fetch data (structure) from the file. 
  7. fprintf= store data into file. 
  8.  fscanf= fetch variable from the file.

Opening a data file 


FILE *fptr 

fptr = fopen (“filename” , ”mode”) 

Where, File name can be “library.txt”, “student.dat” ..etc 


“w” to write/store data in a data file. 

“r” to display/read/retrieve/access data from a datafile. 

“a” to add/append data in existing datafile. 


Store/write data 


fprintf(fptr , ”format specifiers” ,variables); 

Eg; suppose if we want to store name, disease, age and bed number of a patient then, it is written  as 

fprintf(fptr , ”%s %s %d %d”, n, d, a, b); 

Where, variable are initialized as: 

char n[10], d[10]; 

int a, b;


Program example 

1) Create a datafile “patient.txt” and store name, disease, age and bed number of a patient.


[Note: This program will store only a single record. To store multiple records we have to use a loop as following  programs.]


2) Create a datafile “student.txt” and store name, class and marks obtained in 3 different subject for few  students/n-students.



3) Create a datafile “student.txt” and store name, class and marks obtained in 3 different subject until user  press “y” / as per user requirement. 


Add/Append data 

1) A datafile “student.txt” contains name, class and marks obtained in 3 different subjects of a few students.  Write a C program to add 200 more records. 


After 200 iterations, the program will stop and close the file “student.txt”. The file will contain the entered student records, each on a separate line, formatted as:

You can verify the contents of the “student.txt” file after running the program to see the recorded student information.


2) A datafile “student.txt” contains name, class and marks obtained in 3 different subjects of a few students.  Write a C program to add more records until the user presses “y” / as per user requirement.


After the user enters the data, the program writes it to the file “student.txt”.


Read/Display/retrieve/access data from a datafile 


fscanf(fptr , ”format specifiers” ,variables);

Eg; Suppose if we want to display/read name, disease, age and bed number of a patient from data  file then, it is written as

         fscanf(fptr , ”%s %s %d %d”, n, d, &a, &b); 

Where, variable are initialized as: 

char n[10], d[10]; 

int a,b;

EOF: End of file 



2) A datafile “student.txt” contains name, class and marks obtained in 3 different subjects of a few students.  Write a C program to read and display only records whose name is Ram.


3) A datafile “student.txt” contains name, class and marks obtained in 3 different subjects of a few students.  Write a C program to read and display only records who pass in all subjects.


4) A datafile “student.txt” contains name, class and marks obtained in 3 different subjects of a few students.  Write a C program to read and display only records who fail in any one subject.


5) A datafile “student.txt” contains name, class and marks obtained in 3 different subjects of a few students.  Write a C program to read and display only name and percentage of all students.


6) A datafile “student.txt” contains name, class and marks obtained in 3 different subjects of a few students.  Write a C program to read and display only records of all students who secure distinction.


Program: Write a program to read a line and store it in a data file and display the contents.



Program: Write a C program to read N students, record, store them in data file and display the content in  appropriate format by using fprintf and fscanf function. 



Program: Write a program using C language that reads successive records from the new data file and  display each record on the screen in an appropriate format. 



Program: Write a C program to read sentences until the enter key is pressed. Put every word in the data file by  using the fputs( ) fucnction and display the content of the file by using fgets( ) function.



Program: Write a C program to read ages of N students, store them in age.txt file and find out the  average age after reading from the data file.



Program: Write C program to read already created data file student.txt and display its contents if it opens  otherwise print message “The file ……does not exists”.




Some IMP Notes 

Fwrite  S.N.  fprintf
Binary format writing  1.  No binary format.
Size of data.  2.  Size of data is not fix
Number of records.  3.  No number of records.
We store the data in block form so not in  format form. 4. Format string used to store the data in the  format form.
Fixed block size.  5. No block size.


S.N.  Structure  S.N.  Pointer
1.  Structure is use to store the  difference type of data member like  as char, int, float etc. 1. Where is pointer is use to store the  address of another location (variable).
2.  Structure is use to maintain the  records. 2. Whereas pointer is use to create link list.
3.  Structure can’t be use to access the  hardware. 3.  Pointer can be use to access the hardware.
4.  Structure can’t be use to create  memory run time. 4.  But pointer are use to create the memory  runtime.
5.  Structure can be declared as pointer  variable. 5.  Pointer can be declared inside the  structure.


S.N.  Break Keywords (Statement)  S.N.  Continue Keywords (Statement)
1.  The break statement is use to terminate  the loop unconditionally. 1. The continue statement is used return the  pointer at the beginning of the loop.
2.  The break statement can also be use  inside the switch statement. 2. But the continue can be use inside the  switch statement.
3.  The break statement is use to terminate  the loop. 3. The continue statement is use to repeat  set of statements.
4.  Example  

 void main( ) 


 int i; 

 for (i=1; i<=10; i++) 


 If (i==5) 







Output= 1,2,3,4. 

4.  Example 

void main( ) 

 int num; 

 for (num=1; num!=10; num+1) 









Output= 1,2,3,4,5,6,8,9.



S.N.  Array  S.N.  Pointer
1. Array is create continue memory location with  same type. 1.  Pointer creates only one block of  memory but access all memory of  another variable.
2.  Array takes huge of memory.  2.  Pointer takes less and less memory.
3.  Array is to be fixed at the time of declaration.  3.  Whereas pointer size can be change at  the run time.
4. In array we can free the memory run time.  4.  But using pointer the dynamic  allocated memory can be make free at  run time.
5.  If we allocated huge sized of array and we get  few information then unnecessary memory  will be occupied. 5.  But this problem can resolved by using  the pointer.
6.  Using array technique to accessing the array  elements is more different comparison to  pointer. 6.  It is easier than array.


Web Technology is the tools and techniques which enables two or more computing devices to  communicate over a network i.e. Internet.

Web Technology consist of two words, the web refers to the World Wide Web.

WWW is the cyber space containing webpages, documents, and any other resources which are identified  and located with the help of their URLs.

Technology refers to the tools and techniques that makes these resources available on the Web such as,  web browsers to view content of web, Programming languages and frameworks for the development of  websites, Database to store data at back end, protocols for communicating on the web, multimedia  elements etc.


Web development

It is the process of designing and developing website which are hosted through internet or intranet. The  process of developing web can range from developing static page to a complex such as web based  application social media sites, E-commerce.

Web development includes web design, web content development, client side scripting, server side  scripting, web engineering etc. Since, web development consists of several interrelated task which can  be accomplish by different types of developer who focuses on different aspect of web creation.


Scripting Language:

A scripting language is a programming language designed for integrating and communicating with other  programming language. It is used in server side as well as client side. Some of the most widely used  scripting language are JavaScript, VBScript, PHP, Perl, Python, Ruby etc.


JavaScript is a scripting language. A scripting language is a lightweight programming language.  JavaScript code can be inserted into any HTML page, and it can be executed by all types of web  browsers.

JavaScript is used to make web pages interactive. It runs on your visitor’s computer and doesn’t  require constant downloads from your website. JavaScript and Java are completely different  language, both in concept and design.

Unlike HTML, JavaScript is case sensitive-therefore watch your capitalization closely when you write  JavaScript statements, create or call variables, objects and functions.

Application Areas of Scripting Language

⮚ Dynamic web applications.

⮚ Game application and Multimedia.

⮚ Scripting like Ruby and Python are used in statistics and research.

⮚ To automate the process.

⮚ Used to create plugins and extensions for existing applications.


Some of the popular Language are:

  1. Python: Python is a very popular and demanding programming language now because it is suitable for developing very simple to complex applications. Python has simple English like syntax.
  2. Perl: Practical Extraction and Reporting Language, first released in 1987 is a powerful language with advance features. Perl is a stable, cross platform programming language. It is a general purpose programming language originally developed for text manipulation and now used for a wide range of tasks including system administration, web development, network programming,  GUI development, and more.
  3. Ruby: Ruby is a dynamic, open source programming language with a focus on simplicity and productivity. It has an elegant syntax that is natural to read and easy to write.
  4. Bash: A Bash script is a plain text file which contains a series of commands. It is widely available on various operating systems and is a default command interpreter on most GNU/Linux systems.
  5. Node.js: Node.js is used to create dynamic page contents. It can create, open, read, write, delete, and close file on the server.
  1. ASP.net: It is used to develop dynamic websites, web applications, and web services. ASP.NET is a web application framework developed and marketed by Microsoft to allow programmers to build dynamic web sites.
  2. VBScript: Visual Basic Script (VBScript) is an open source web programming language developed by Microsoft. It is superset of JavaScript and adds optional static typing class based object oriented programming VBScript is lightweight scripting language. As VBScript is only used by IE browsers  JavaScript is preferred over VBScript.
  3. JavaScript: JavaScript is most well-known and widely used scripting language for web pages. All javascript files are stored in file having is extension. JavaScript is generally used for making websites interactive and dynamic.
  4. jQuery: JQuery is a JavaScript library that simplifies writing code and enables rapid web development. JQuery simplifies HTML document traversing and manipulation, and browser event handling. The main concept of jQuery is “write less, do more”.
  5. PHP: Hypertext Preprocessor (PHP) is widely used scripting language. PHP scripts are executed on the server. It is used to manage dynamic content, databases, session tracking and building e commerce sites. It is integrated with a popular database MySQL.


Difference between Scripting Language and Programming Language

S.N. Scripting Language S.N. Programming Language
1. Scripting language are platform-specific. 1. Programming language are platform independent.
2. Most of the scripting languages are  interpreted. 2. Most of the programming language are  complied.
3. Scripting language runs slower than  programming language. 3. Programming languages runs faster than  scripting language.
4. Developer has to write less code compared  to programming language. 4. Developer has to write much code

compared to scripting language.

5. We cannot create standalone application  with scripting language only. 5. We can create standalone application with  programming language only.
6. Examples, JavaScript, VBScript, Python,  Perl, ASP etc. 6. Examples, C, C++, Java etc.
7. Scripting languages run inside other programs. It is dependent on other  programming language. 7. It is not dependent on other programs to  run. It is independent.


Server side and client side programming

Client-Side Scripting programming

Client-side scripting is performed to generate a code that can run on the client side i.e (front end) browser  without needing the server-side (back end) processing. Basically, client-side scripts are placed inside an  HTML document.

The client-side scripting can be used to layout the content of the web. For example, when a user makes a  request through web browser for a web page to the server, it just sent the HTML and CSS as plain text, and  the browser interprets and renders the content of web in the client end (user).

Client-side scripting is designed to run as a scripting language which can be executed by web browser. Front end developer is someone who design and develop client side of a website. Generally he or she  works in user interface (UI) of a website. Front end developer must be at least fluent in three different  languages i.e. HTML, CSS, JavaScript whereas, there are several other libraries which can be used for front  end development.

Advantages of Client Side Scripting:

  1. Immediate response to users.
  2. Enhance the appearance of websites.
  3. More responsive design and interaction with the user.
  4. It does not need to send requests to the server hence reduces the load on server.
  5. Loading time of a page is faster.
  6. Reduces the network traffic.
  7. It is reusable.

Disadvantages of Client Side Scripting:

  1. All browsers may not support client side script.
  2. The code is not secure because anyone can look at the code.
  3. Users can disable the client side scripts so required content may not be displayed.
  4. Database connection is not possible with client side scripting.
  5. Dynamic content cannot be displayed.
Server-Side Scripting programming

Server-side scripting also known as back-end runs on the server where the application is hosted. Server side is used to serve content depending upon the user request. Back end helps to create dynamic web  based application that allows user to interact and communicate with the application. Back end language  also helps to connect front end with database. So that, user can store and retrieve data as per the  requirement. Back-end developer is responsible for server-side programming. Some of the popular  server-side (back-end) scripting language are ASP, JavaScript (using SSJS (Server-side JavaScript e.g.  node.js), Perl, PHP, Ruby, Python etc.

The client-side scripting emphasizes making the interface of the web application or website (UI) more  appealing and functional. Whereas, server-side scripting emphasizes on data accessing methods, error  handling and fast processing etc.

Advantages of Server Side Scripting:

  1.  You can create dynamic pages.
  2.  Can connect to database that resides on the web server.
  3.  Can access files from the server to client browser. Users are not able to block the contents from  server.
  4.  The actual code is not visible to the client.
  5.  Authentication and verification of user is possible.
  6.  It supports many databases like MySQL Oracle.
  7.  Efficient storage and delivery of information.
  8.  Customized user experience.
  9.  Controlled access to content.
  10.  Notification and communication.
  11.  Users do not need to download plug-in like java or flash.
  12.  The content management system (CMS) makes editing simpler.

Disadvantages of Server Side Scripting:

  1. The scripting software has to be installed on the server.
  2. The script takes more time to execute.
  3. It requires a large amount of memory space in the server computer.
  4. Implementation cost is high.
  5. If a lot of users are accessing server data, server may crash due to overload.

Note: Full-stack developer understand both Front end and back end development process. They can  accomplish entire project. Full stack developer must have expertise in client site and server side Scripting  language. Moreover, he/she has a great knowledge of integrating database with the application.


Comparison between Client-side and Server-side Scripting

This section elaborates the fundamental differences between client-side and server-side scripts:

  1. The client-side script is executed at the front-end in the client’s browser while the server-side script is executed at the back end with a web server.
  2. The client-side script is visible to the user of the web browser while the server-side script is hidden. 3. The client-side script is not secure while the server-side script is secure.
  3. The client-side script does not need to interact with the server while the server-side script needs a web server to be processed.
  4. The client-side script is executed on a local computer while the server-side script is executed on a remote computer.
  5. The client-side script has a faster response time than the server-side script.
  6. Client-side script is executed after the browser receives the web pages sent by the server while the server-side script cannot execute the client-side script.
  7. The client-side script cannot connect with the database while the server-side script can connect with the database present on the server-side.
  8. The client-side script cannot access the files while the server-side script can access and manipulate the files present at the webserver.
  9. The client-side script helps create interactive web pages while the server-side script helps create web pages with dynamic data.


Difference between Server Side Scripting & Client Side Scripting

S.N. Server Side Scripting S.N. Client Side Scripting
1. The Server executes the server side  scripting. 1. The client (web browser) executes the  client side scripting.
2. It can be used to connect database  on the web server. 2. It cannot be used to connect to the  database on the web server.
3. Server side scripting response is  slower. 3. Client side scripting response is faster.
4. Source code is not visible to the user  so it is secure. 4. Source code is visible to user so it is  relatively insecure.
5. Users can not block server side  scripting. 5. Users can block client side scripting
6. Examples: PHP, ASP.NET, ASP, Ruby  on rails, Python, Perl. 6. Examples: JavaScript, VBScript
7. It does not depend on client. Any  server side technology can be used. 7. It depends on browser and version of the  browser.


Internet Technology

The Internet is the global system of interconnected computer networks that uses the Internet protocol  suite to communicate between networks and devices. It is a network of networks that consists of private,  public, academic, business, and government networks of local to global scope, linked by a broad array of  electronic, wireless, and optical networking technologies. The Internet carries a vast range of information  resources and services, such as the inter-linked hypertext documents and applications of the World Wide  Web, electronic mail, telephony, and file sharing.

Static Website:

Static Web pages are very simple. It is written in languages such as HTML, CSS, etc. Static websites are the websites that doesn’t change the content or layout dynamically with every request to  the web server. Static websites display exactly the same information whenever anyone visits it. User  sees the updated content of Static Website only when a web author manually updates them with a text editor or any web editing tool used for creating websites. Static web pages do not have to be simple  plain text. They can feature multiple design and even videos.

Features of Static Websites:

❏  Static websites are the simplest kind of website that you can build.

❏  Every viewer will see the exactly same text, multimedia design or video every time he/she visits the  website until you alter that page’s source code.

❏  Static websites are written with the help of HTML and CSS.

❏  The only form of interactively on a static website is hyperlink.

❏  Static website can be used for the information that doesn’t change substantially over months or  even years.

❏  Static pages are easy and simple to understand, secure, less prone to technology errors and  breakdown and easily visible by search engines.

❏  HTML was the first tool with which people had begun to create static web pages. Static websites provide flexibility.

❏  Lightweight.

❏  Static websites perform faster and well than dynamic ones.

Advantages of Static websites:

  1. Static websites are highly cost-effective for publishing.
  2. They require less coding and technical knowledge.
  3.  Static websites are easier to make.
  4.  Static websites are quick to develop.
  5. Static websites are cheap to host.
  6.  A static website contains data which is immutable.
  7.  Static websites are beginner level. A programmer with knowledge of HTML, CSS, and JavaScript   can build static websites.
  8.  It’s easy to create and host online.
  9.  Static websites are more secure.

Disadvantages of Static Websites:

  1. Requires web development expertise to update site.
  2. Site not as useful for the user.
  3. Content can get stagnant.
  4. Send the same response for every request.
  5. Dynamic functionality works only on the client side.
Dynamic website:

Dynamic websites are those websites that changes the content or layout with every request to the  webserver. These websites have the capability of producing different content for different visitors from  the same source code file. There are two kinds of dynamic web pages i.e. client side scripting and server  side scripting. The client-side web pages changes according to your activity on the web page. On the  server-side, web pages are changed whenever a web page is loaded.

Example: login & signup pages, application & submission forms, inquiry and shopping cart pages. A  Typical Architecture of dynamic website

There are different languages used to create dynamic web pages like PHP, ASP, .NET and JSP.

Whenever a dynamic page loads in browser, it requests the database to give information depending  upon user’s input. On receiving information from the database, the resulting web page is applied to  the user after applying the styling codes.

Features of dynamic webpage:

❏  These websites are very flexible.

❏  In these websites the content can be quickly changed on the user’s computer without new page  request to the web browser.

❏  In these websites the owner have the ability to simply update and add new content to the site.

❏  These websites are featured with content management system, e-commerce system and intranet  or extranet facilities.

❏  Most of the dynamic web content, is assembled on the web using server-scripting languages.

Advantages of dynamic webpage:

  1. It provides more functional websites.
  2. It is very easy to update.
  3. It helps in the search engines because new content brings people back to the site.
  4. These are interactive websites because these can be customized.
  5. These websites can work as a system to allow staff or users to collaborate.
  6. It’s easy to modify or update data.
  7. It provides a user-friendly interactive interface for users.
  8. Proves smooth navigation.
  9. provide interactive user interface
  10. It provides a better user experience.
  11. It provides real-time data.

 Disadvantages of dynamic web pages:

  1. These types of websites are complex.
  2. These are more expensive to develop.
  3. Hosting of these websites is also costlier.
  4. It requires a rapid, high-end web server.
  5. High production costs.
  6. Slow to load content.
  7. Client will require a skilled programmer to build a dynamic website.
  8. Hosting a website is costly as compared to a dynamic website.
  9. Low speed compared to a static website.

Application of Dynamic Website:

➢ Online booking system:

➢  E-commerce website.

➢  Voting or polls,

➢  Forums

➢  E-newsletter.



JavaScript is a lightweight, interpreted programming language. It is designed for creating network-centric  applications. It is complementary to and integrated with Java. JavaScript is very easy to implement because  it is integrated with HTML. It is open and cross-platform.

This tutorial has been prepared for JavaScript beginners to help them understand the basic functionality  of JavaScript to build dynamic web pages and web applications.


⮚  JavaScript is a lightweight, interpreted programming language.

⮚  Designed for creating network-centric applications.

⮚  Complementary to and integrated with Java.

⮚  Complementary to and integrated with HTML.

⮚  It is case sensitive language.

⮚  JavaScript is supportable in operating system.

⮚  It provides good control to the users over the web browsers.

Advantages of JavaScript:

  1. Less server interaction: You can validate user input before sending the page off to the server. This saves server traffic, which means fewer loads on your server.
  2. Easy to learn: By learning few commands and simple rules of syntax, you can easily build applications using JavaScript.
  3. Immediate feedback to the visitors: They don’t have to wait for a page reload to see if they have forgotten to enter something.
  4. Increased interactivity: You can create interfaces that react when the user hovers over them with a mouse or activates them via the keyboard.
  5. Quick Development: Scripts can be developed in short period of time
  6. Richer interfaces: You can use JavaScript to include such items as drag-and-drop components and sliders to give a Rich Interface to your site visitors.
  7. Transmitting information: About the users’ reading habits and browsing activities to various websites. Web pages frequently do this for web analytics, ad tracking personalization or other purposes.
  8. Easy Debugging and Testing: As JavaScript is interpreted line by line, it is easy to find error and make changes.
  9. Interactive content, for example games, and playing audio and video.
  10. Validating input values of a Web form to make sure that they are acceptable before being submitted to the server.

Uses of JavaScript:

⮚  Client side validation

⮚  Dynamic drop down menus.

⮚  Displaying date and time.

⮚  Displaying pop-up windows and dialog boxes

⮚  Displaying clocks.

⮚  Event handling.

⮚  Developing Mobile applications

⮚  Creating web browser based games.

⮚  Building web servers

⮚  Adding interactivity to website.


Adding JavaScript to HTML

JavaScript, also known as JS, is one of the scripting (client-side scripting) languages, that is usually used in  web development to create modern and interactive web-pages. The term “script” is used to refer to the  languages that are not standalone in nature and here it refers to JavaScript which run on the client  machine.

In other words, we can say that the term scripting is used for languages that require the support of another  language to get executed. For example, JavaScript programs cannot get executed without the help  of HTML or without integrated into HTML code.

  1. Embedding code
  2. Inline code
  3. External file
  1. Embedding code: To add the JavaScript code into the HTML pages, we can use the <script>…..</script> tag of the HTML that  wrap around JavaScript code inside the HTML program. Users can also define JavaScript code in  the <body> tag(or we can say body section) or <head> tag because it completely depends on the structure of the web page that the users use.


We can also define the JavaScript code in the <body> tags or body section.

Let’s understand through an example.



  1. Inline code:- Generally, this method is used when we have to call a function in the HTML event attributes. There are  many cases (or events) in which we have to add JavaScript code directly eg., OnMove event, OnClick, etc. Let’s see with the help of an example, how we can add JavaScript directly in the html without using  the <script>…. </script> tag.

Let’s look at the example.


  1. External file:- We can also create a separate file to hold the code of JavaScript with the (.js) extension and later  incorporate/include it into our HTML document using the src attribute of the <script> tag. It becomes very  helpful if we want to use the same code in multiple HTML documents. It also saves us from the task of  writing the same code over and over again and makes it easier to maintain web pages.

In this example, we will see how we can include an external JavaScript file in an HTML document. Let’s understand through a simple example.


Now let’s create separate JavaScript file = Hello.js



JavaScript Fundamentals


JavaScript statements are written within <script>…..</script>. The <script> tag alerts the browser  program to start interpreting all the statements between these tags as a script. A simple syntax of your  JavaScript will appear as follows:



         block of Statements  



JavaScript statements are composed of Values, Operators, Expressions, Keywords, and Comments. The  program consists of many statements. The statements are executed, one by one, in the same order as  they are written. It is often called JavaScript code.

var area = l*b;


JavaScript comments

The JavaScript comments are meaningful way to deliver message. It is used to add information about the  code, warnings or suggestions so that end user can easily interpret the code.

The JavaScript comment is ignored by the JavaScript engine i.e. embedded in the browser. There are two types of comments in JavaScript.

  1. Single-line Comment
  2. Multi-line Comment


  1. Single line Comment

It is represented by double forward slashes (//). It can be used before and after the statement. Let’s see the example of single-line comment i.e. added before the statement.


Let’s see the example of single-line comment i.e. added after the statement.


  1. Multi line Comment

It can be used to add single as well as multi line comments. So, it is more convenient. It is represented by forward slash with asterisk the asterisk with forward slash. For example:

/* your comment here */

It can be used before, after and middle of the statement.



Whitespace and Line Breaks: 

JavaScript ignores spaces, tabs, and newlines that appear in JavaScript programs. To make a code  readable and understandable, formatting and indenting the code by using several spaces, tabs, and  newlines can be used freely in the program.

Case Sensitivity: 

JavaScript is a case-sensitive language. The keywords, variables, functions names, and any other  identifiers must always be typed with a consistent capitalization of letters. So the identifiers Time and  TIME will convey different meanings in JavaScript.


JavaScript can “display” data in different ways: It defines the ways to display the output of a given code.  The output can be display by using four different ways which are listed below:


Basic Display function in JavaScript

  1. Document.write

Using document.write( ), the output can be displayed in browser page.



Using innerHTML, the output can be displayed into the HTML element. The innerHTML property sets or  returns the HTML content (innerHTML) of an element.



  1. Window. Alert

Using window.alert( ), the output can be displayed into an alert box. window.confirm() and  window.prompt() are also other method to output into an alert box.



  1. Console.log

Using console.log( ), the output can be displayed into the browser console. To use console of web  browser, right click in web browser and select inspect. The console will display.



Reserved Words:

Lists of all the reserved words in JavaScript are given in the following table. They cannot be used as JavaScript variables, functions, methods, loop labels, or any object names.


JavaScript Data Types

JavaScript provides different data types to hold different types of values. There are two types of data types  in JavaScript.

  1. Primitive data type
  2. Non-primitive (reference) data type

JavaScript is a dynamic type language, means you don’t need to specify type of the variable because it is  dynamically used by JavaScript engine. You need to use var here to specify the data type. It can hold any  type of values such as numbers, strings etc. For example:

var a=40; //holding number

var b=”Rahul”; //holding string


JavaScript primitive data types

There are five types of primitive data types in JavaScript. They are as follows:

Data Type Description
1. String represents sequence of characters e.g. var str=”hello”;
2. Number represents numeric values e.g. var a=100;
3. Boolean represents Boolean value either false or true
4. Undefined represents undefined value. E.g. var address=”Bharaptur”  address= undefined
5. Null represents null i.e. no value at all.


JavaScript non-primitive (reference) data types

The non-primitive data types are as follows:

Data Type Description
1. Object represents instance through which we can access members
2. Array represents group of similar values
3. RegExp represents regular expression


JavaScript Variable

  1. JavaScript Local variable
  2. JavaScript Global variable

A JavaScript variable is simply a name of storage location. There are two types of variables in JavaScript: local variable and global variable.

There are some rules while declaring a JavaScript variable (also known as identifiers).

  1. Name must start with a letter (a to z or A to Z), underscore ( _ ), or dollar( $ ) sign.
  2. After first letter we can use digits (0 to 9), for example value1.
  3. Reserved words cannot be used as names.
  4. JavaScript variables are case sensitive, for example x and X are different variables.

Correct JavaScript variables

  1. var x = 10;
  2. var _value=”Hari”;

Incorrect JavaScript variables

  1. var 123=30;
  2. var *aa=320;

Example of JavaScript variable

Let’s see a simple example of JavaScript variable.



JavaScript Operators

JavaScript operators are symbols that are used to perform operations on operands. For example:

var sum=10+20;

Here, + is the arithmetic operator and = is the assignment operator.

There are following types of operators in JavaScript.

  1. Arithmetic Operators
  2. Comparison (Relational) Operators
  3. Bitwise Operators
  4. Logical Operators
  5. Assignment Operators
  6. Special Operators
  7. Unary Operator
  8. String Operator
  9. Conditional Operator


JavaScript Arithmetic Operators

Arithmetic operators are used to perform arithmetic operations on the operands. The following operators  are known as JavaScript arithmetic operators.

Operator Description Example
 + Addition 10+20 = 30
  Subtraction 20-10 = 10
 * Multiplication 10*20 = 200
 / Division 20/10 = 2
 % Modulus (Remainder) 20%10 = 0
 ++ Increment var a=10; a++; Now a = 11
  Decrement var a=10; a–; Now a = 9





JavaScript Comparison Operators

The JavaScript comparison operator compares the two operands. The comparison operators are as  follows:

Operator Description Example
 == Is equal to 10==20 = false
 != Not equal to 10!=20 = true
 > Greater than 20>10 = true
 >= Greater than or equal to 20>=10 = true
 < Less than 20<10 = false
 <= Less than or equal to 20<=10 = false






JavaScript Bitwise Operators

The bitwise operators perform bitwise operations on operands. The bitwise operators are as follows:

Operator Description Example
1) & Bitwise AND (10==20 & 20==33) = false
2) | Bitwise OR (10==20 | 20==33) = false
3) ^ Bitwise XOR (10==20 ^ 20==33) = false
4) ~ Bitwise NOT (~10) = -10
5) << Bitwise Left Shift (10<<2) = 40
6) >> Bitwise Right Shift (10>>2) = 2
7) >>> Bitwise Right Shift with Zero (10>>>2) = 2


JavaScript Logical Operators

The following operators are known as JavaScript logical operators.

Operator Description Example
 && Logical AND (10==20 && 20==33) = false
 || Logical OR (10==20 || 20==33) = false
 ! Logical Not !(10==20) = true


JavaScript Assignment Operators

The following operators are known as JavaScript assignment operators.

Operator Description Example
 = Assign 10+10 = 20
 += Add and assign var a=10; a+=20; Now a = 30
 -= Subtract and assign var a=20; a-=10; Now a = 10
 *= Multiply and assign var a=10; a*=20; Now a = 200
 /= Divide and assign var a=10; a/=2; Now a = 5
 %= Modulus and assign var a=10; a%=2; Now a = 0


JavaScript Special Operators

The following operators are known as JavaScript special operators.

Operator Description
 (?:) Conditional Operator returns value based on the condition. It is like if-else.
 , Comma Operator allows multiple expressions to be evaluated as single  statement.
 Delete Delete Operator deletes a property from the object.
 In In Operator checks if object has the given property
 Instanceof checks if the object is an instance of given type
 new creates an instance (object)
 typeof checks the type of object.
 Void it discards the expression’s return value.


JavaScript Bitwise Operators

Bit operators work on 32 bits numbers.

Any numeric operand in the operation is converted into a 32 bit number. The result is converted back to  a JavaScript number.

Operator Description Example Same as Result Decimal
& AND 5 & 1 0101 & 0001 0001 1
| OR 5 | 1 0101 | 0001 0101 5
~ NOT ~ 5 ~0101 1010 10
^ XOR 5 ^ 1 0101 ^ 0001 0100 4
<< left shift 5 << 1 0101 << 1 1010 10
>> right shift 5 >> 1 0101 >> 1 0010 2


Functions and Function Return

A JavaScript function is a block of code designed to perform a particular task. A function is a go of reusable  code which can be called anywhere in your program. This eliminates the need of writing the same code  again and again. It helps programmers in writing modular codes. Function allow a programmer to divide a  big program into a number of small and manageable function.

Advantages of Using Function: 

⮚ You can’t do anything in JavaScript without function.

⮚ Functions increases code reusability.

⮚ Function helps to structure the code properly.

⮚ Functions make code less complex.

⮚ Functions make code more readable and extendable.

⮚ Functions can be called anywhere in the program.

⮚ Functions helps program developers to write the modular codes.

⮚ Function also allows a programmer to divide a big program into a number of small and manageable functions.


Function Definition

Before we use a function, we need to define it. The most common way to define a function in JavaScript  is by using the function keyword, followed by a unique function name, a list di parameters (that might be  empty), and a statement block surrounded by curly braces.


<script type=”text/javascript”>  

function function_name (parameter-list) 




Calling a Function

The code written inside a function does not execute unless it is called. To call a function somewhere later  in the script, you would simply need to write the name of that function as shown in the following code.

Example 1:


Example 2:



Function Parameters

A function can take multiple parameters separated by comma. The function parameters can have value  of any data type.




Function Return

The return statement is used to return a particular value from the function to the function caller. The  function will stop executing when the return statement is called. The return statement should be the last  statement in a function because the code after the return statement will be unreachable.



Above program is a simple example of using the return statement. Here, returning the result of the  product of two numbers and returned the value to the function caller.

The variable res is the function caller; it calls the function fun() and passes two parameters as the  arguments of the function.

The result will be store in the res variable. Final output 240 is the product of arguments 12 and 20.


Control Structures

  1. If-else
  2. switch case
  3. for loop
  4. while loop
  5. do while loop

The JavaScript if-else statement is used to execute the code whether condition is true or false. There are  three forms of if statement in JavaScript.

  1. If Statement
  2. If else statement
  3. if else if statement


JavaScript If statement

It evaluates the content only if expression is true. The signature of JavaScript if statement is given below.



//content to be evaluated  



Let’s see the simple example of if statement in JavaScript.



JavaScript If…else Statement

It evaluates the content whether condition is true of false. The syntax of JavaScript if-else statement is  given below.


Let’s see the example of if-else statement in JavaScript to find out the even or odd number.



JavaScript If…else if statement

It evaluates the content only if expression is true from several expressions. The signature of JavaScript if  else if statement is given below.



//content to be evaluated if expression1 is true  


else if(expression2) 


//content to be evaluated if expression2 is true  


else if(expression3) 


//content to be evaluated if expression3 is true  




//content to be evaluated if no expression is true  



Let’s see the simple example of if else if statement in JavaScript.



Write a program to input a number and check that is positive, negative or not.



JavaScript Switch

The JavaScript switch statement is used to execute one code from multiple expressions. It is just  like else if statement that allow us to choose only one option among the many given options. But  it is convenient than if..else..if because it can be used with numbers, characters etc.

The signature of JavaScript switch statement is given below.



case value1:  

code to be executed;  


case value2:  

code to be executed;  




code to be executed if above values are not matched;  }


Let’s see the simple example of switch statement in JavaScript.



JavaScript Loops / Iterations

The processing of repeatedly executing the block of statements is called iteration or looping. Loops are  used to repeat the execution of a block of code. The JavaScript loops are used to iterate the piece of  code using for, while, do while. It makes the code compact. It is mostly used in array. There are four types of loops in JavaScript.

  1. for loop
  2. while loop
  3. do-while loop


JavaScript For loop

For loop is used to execute a set of statements for given number of times. The JavaScript for loop iterates  the elements for the fixed number of times. It should be used if number of iteration is known. The syntax  of for loop is given below.

for (initialization; condition; increment)  


 code to be executed  



Let’s see the simple example of for loop in JavaScript.



JavaScript While loop:

The while loop is an entry controlled loop in which condition is checked before the execution of loop.


while (condition)  


 // code block to be executed 



Example, Write a program to display even number from 1 to 20.



JavaScript do while loop

The JavaScript do while loop iterates the elements for the infinite number of times like while loop. But,  code is executed at least once whether condition is true or false. The syntax of do while loop is given  below.



 code to be executed  

}while (condition);





Some JavaScript Program Examples

  1. Write a JavaScript program to input two numbers and find out its sum.





Object based Programming with JavaScript and Event Handling


Object is a non-primitive data type in JavaScript. Object is like any other variable but it is quite differ from  variable. The variable can hold only one value but object can hold multiple values. The object holds  multiple values in terms of properties and methods. Properties can hold values of primitive data types  and methods are functions.

An object is defined simple way as like a variable. The object is defined with a unique object name and  the curly brackets { } is used to include properties and methods. The variables within the object is known  as properties and the function within the object is known as methods. The properties or method are  written as name: value pairs. The name and value separated by a colon. The period ‘.’ is used to access  value to object.


var object_name = { name: value1, name2: value2, nameN: valueN };



In the above example, object name is defined as emp and it has three properties id, name and salary. The  value of object can be accessed easily using object name period and properties name.


Creating Objects in JavaScript

There are 3 ways to create objects.

  1. By object literal
  2. By creating instance of Object directly (using new keyword)
  3. By using an object constructor (using new keyword)

1) JavaScript Object by object literal

The syntax of creating object using object literal is given below:



As you can see, property and value is separated by : (colon). Let’s see the simple example of creating object  in JavaScript.



In the above example, method is defined as move. The method can be accessed easily using  object name period and method name.


2) By creating instance of Object

The syntax of creating object directly is given below:

var objectname=new Object(); 


Here, new keyword is used to create object. Let’s see the example of creating object directly.



3) By using an Object constructor

Here, you need to create function with arguments. Each argument value can be assigned in the current  object by using this keyword.

The this keyword refers to the current object.

The example of creating object by object constructor is given below.



Document Object Model

The document object represents the whole html document. When html document is loaded in the  browser, it becomes a document object. It is the root element that represents the html document. It has  properties and methods. By the help of document object, we can add dynamic content to our web page. As mentioned earlier, it is the object of window. So window.document is same as a document.


Properties of document object

Let’s see the properties of document object that can be accessed and modified by the document object.

JavaScript gets all the power it needs to create dynamic HTML:

⮚ JavaScript can change all the HTML elements in the page

⮚ JavaScript can change all the HTML attributes in the page

⮚ JavaScript can change all the CSS styles on the page

⮚ JavaScript can remove existing HTML elements and attributes

⮚ JavaScript can add new HTML elements and attributes

⮚ JavaScript can react to all existing HTML events in the page

⮚ JavaScript can create new HTML events in the page


Methods of document object

We can access and change the contents of document by its methods. The important methods of document  object are as follows:

Method Description
write(“string”) writes the given string on the document.
writeln(“string”) writes the given string on the document with newline character at the end.
getElementById() returns the element having the given id value.
getElementsByName() returns all the elements having the given name value.
getElementsByTagName() returns all the elements having the given tag name.
getElementsByClassName() returns all the elements having the given class name.


Accessing field value by document object

In this example, we are going to get the value of input text by user. Here, we are  using document.form1.name.value to get the value of name field. Here, document is the root element  that represents the html document. form1 is the name of the form. name is the attribute name of the  input text. value is the property, that returns the value of the input text.

Let’s see the simple example of document object that prints name with welcome message.



  1. getElementById( )

The document.getElementById() method returns the element of specified id. We can use  document.getElementById() method to get value of the input text. But we need to define id for the  input field.


In the example above, getElementById is a method, while innerHTML is a property.


In the example above, getElementById is a method, while innerHTML is a property.

Let’s see the simple example of document.getElementById() method that prints cube of the given  number.



  1. getElementsByName()

The document.getElementsByName() method returns all the element of specified name. The syntax of

the getElementsByName() method is given below:

document.getElementsByName(“name”) Here, name is required.


Example of document.getElementsByName() method

In this example, we going to count total number of genders. Here, we are using getElementsByName() method to get all the genders.



  1. document.getElementsByTagName()

The document.getElementsByTagName() method returns all the element of specified tag name. The syntax of the getElementsByTagName() method is given below:


Example of document.getElementsByTagName() method

In this example, we going to count total number of paragraphs used in the document. To do this, we have

called the document.getElementsByTagName(“p”) method that returns the total paragraphs.


Another example of document.getElementsByTagName() method




The innerHTML property can be used to write the dynamic html on the html document. It is used mostly in the web pages to generate the dynamic html such as registration form,  comment form, links etc.

Example of innerHTML property

In this example, we are going to create the html form when user clicks on the button. In this example, we are dynamically writing the html form inside the div name having the id  mylocation. We are identifying this position by calling the document.getElementById() method.



JavaScript Events

The change in the state of an object is known as an Event. In html, there are various events which  represents that some activity is performed by the user or by the browser. When JavaScript code is included  in HTML, JavaScript react over these events and allow the execution. This process of reacting over the  events is called Event Handling. Thus, JavaScript handles the HTML events via Event Handlers.

For example, when a user clicks over the browser, add js code, which will execute the task to be performed  on the event.

Some of the HTML events and their event handlers are:

Mouse events:

Event Performed Event Handler Description
Click Onclick When mouse click on an element
Mouseover Onmouseover When the cursor of the mouse comes over the  element
Mouseout Onmouseout When the cursor of the mouse leaves an element
Mousedown Onmousedown When the mouse button is pressed over the element
Mouseup Onmouseup When the mouse button is released over the element
Mousemove Onmousemove When the mouse movement takes place.


Keyboard events:

Event Performed Event Handler Description
Keydown & Keyup onkeydown & onkeyup When the user press and then release the  key


Form events:

Event Performed Event Handler Description
Focus onfocus When the user focuses on an element
Submit onsubmit When the user submits the form
Blur Onblur When the focus is away from a form element
Change onchange When the user modifies or changes the value of a form  element


Window/Document events:

Event Performed Event Handler Description
Load Onload When the browser finishes the loading of the page
Unload onunload When the visitor leaves the current webpage, the browser  unloads it
Resize Onresize When the visitor resizes the window of the browser


Let’s discuss some examples over events and their handlers.

Click Event



Mouse Over Event:



Focus Event:



Keydown Event:



Load event:



Image Object

Form Validation

It is important to validate the form submitted by the user because it can have inappropriate values. So, validation is must to authenticate user.

JavaScript provides facility to validate the form on the client-side so data processing will be faster than  server-side validation. Most of the web developers prefer JavaScript form validation.

Through JavaScript, we can validate name, password, email, date, mobile numbers and more fields.

In this example, we are going to validate the name and password. The name can’t be empty and password  can’t be less than 6 characters long.

Here, we are validating the form on form submit. The user will not be forwarded to the next page until  given values are correct.



JavaScript Retype Password Validation



Number Validation

Let’s validate the text field for numeric value only. Here, we are using isNaN() function.



JavaScript validation with image

Let’s see an interactive JavaScript form validation example that displays correct and incorrect  image if input is correct or incorrect.



JavaScript email validation

We can validate the email by the help of JavaScript.

There are many criteria that need to be follow to validate the email id such as:

o Email id must contain the @ and . character

o There must be at least one character before and after the @.

o There must be at least two characters after. (Dot).

Let’s see the simple example to validate the email field.



JavaScript Programs
  1. This program adds 5 numbers and writes the answer as an HTML output.



  1. JavaScript program to check whether a number is a prime number or not. This program does not take input from user.



Data Format Validation: 

Secondly, the data that is entered must be checked for correct form and value. Your code must include  appropriate logic to test the correctness of data.




JQuery is a fast, small, lightweight, “write less, do more”, and feature-rich JavaScript library. It makes  things like HTML document traversal and manipulation, event handling animation, and Ajax much simpler  with an easy-to-use API (Application Programming Interface) that works across browsers. With a  combination of versatility and extensibility, jQuery has changed the way that millions of people write  JavaScript.

JQuery is a JavaScript library. The purpose of jQuery is to make it much easier to use JavaScript on your  website. JQuery simplifies a lot of the complicated things from JavaScript like AJAX (Asynchronous  JavaScript and XML) calls and DOM (Document Object Model) manipulation. Some of the biggest  companies which uses jQuery on the Web are

  1. Google
  2. Microsoft
  3. IBM


Features of jQuery: 

Some of important feature of jQuery are listed as follows:

  1. The jQuery is very small, fast, lightweight JavaScript library
  2. It is very fast and extensible.
  3. It has a lot of built-in animation effects which can use directly in websites.
  4. It is used to improve the performance of an application.
  5. It is used to develop browser compatible web applications effectively.
  6. It uses mostly new features of new browsers.
  7. It is platform-independent.
  8. It is used to develop a responsive web application.


Server Side Scripting Using PHP:

Server side script are discrete blocks of program code that execute on a web server (as opposed to a web client) computer. They are generally used to create Dynamic web pages.This means that the page displayed to the user does not exist as a document on the server in its own right, and is only brought into existence in response to a user request. Often, a server-side script provides the interface between a web-based user interface and a database that resides on a web server. PHP is a server side scripting language used to create dynamic web pages. PHP is well suited for web development. PHP stands for hypertext preprocessor. It is an interpreted language. It is embedded in HTML. It is an open source language.


Some important points need to be notice about PHP are as followed:

  1. PHP stands for Hypertext Preprocessor.
  2. PHP is an interpreted language, i.e., there is no need for compilation.
  3. PHP is faster than other scripting languages, for example, ASP and JSP.
  4. PHP is a server-side scripting language, which is used to manage the dynamic content of the website.
  5. PHP can be embedded into HTML.
  6. PHP is an object-oriented language.
  7. PHP is an open-source scripting language.
  8. PHP is simple and easy to learn language.


Features of PHP

  1. Simple
  2. Interpreted
  3. Faster
  4. Open Source
  5. Platform Independent
  6. Case Sensitive
  7. Error Reporting
  8. Real-Time Access Monitoring
  9. Loosely Typed Language


Characteristics of PHP

  1. Simplicity
  2. Efficiency
  3. Security
  4. Flexibility
  5. Familiarity


Advantages of PHP / what problem does it solve.

  1. PHP is Free
  2. PHP is Cross Platform
  3. PHP is widely used
  4. PHP hides its complexity
  5. PHP is built for Web Programming


Introduction to PHP: 

PHP is an open-source, interpreted, and object-oriented scripting language that can be executed at the  server-side. PHP is well suited for web development. Therefore, it is used to develop web applications (an  application that executes on the server and generates the dynamic page.).

Before learning PHP, you must have the basic knowledge of HTML, CSS, and JavaScript. So, learn these  technologies for better implementation of PHP.

HTML – HTML is used to design static web page.

CSS – CSS helps to make the webpage content more effective and attractive.

JavaScript – JavaScript is used to design an interactive website.


PHP is widely used in web development nowadays. PHP can develop dynamic websites easily. But you  must have the basic the knowledge of following technologies for web development as well.

  1. HTML
  2. CSS
  3. JavaScript
  4. Ajax
  5. XML and JSON
  6. jQuery


Why use PHP / Strengths of PHP

PHP is a server-side scripting language, which is used to design the dynamic web applications with MySQL database.

  1. It handles dynamic content, database as well as session tracking for the website.
  2. You can create sessions in PHP.
  3. It can access cookies variable and also set cookies.
  4. It helps to encrypt the data and apply validation.
  5. PHP supports several protocols such as HTTP (Hypertext Transfer Protocol), POP3 (Post office Protocol-3), SNMP (Simple Network Management Protocol), LDAP (Lightweight Directory Access Protocol), IMAP (Internet Message Access Protocol), and many more.
  6. Using PHP language, you can control the user to access some pages of your website.
  7. As PHP is easy to install and set up, this is the main reason why PHP is the best language to learn.
  8. PHP can handle the forms, such as – collect the data from users using forms, save it into the database, and return useful information to the user. For example – Registration form.


Weaknesses of PHP

  1. PHP’s main strength flexibility is also its weakness. It can be a little too forgiving of errors.
  2. With no strict rules, inexperienced programmers have the freedom to create some very bad solutions to simple problems.
  3. Bad packages that got popular in the community are still reused when developers are trying something new or rushed for time. Some of these mistakes lead to security risks.
  4. As a mature tool PHP has some legacy baggage. There are lots of internal consistencies, especially surrounding references and values.
  5. This is mostly due to updates, which add features that clash with earlier features,
  6. PHP is an interpreted language, which can reduce speed.
  7. PHP 7 increased performance over previous versions by a significant amount while maintaining most language compatibility.
  8. The changes didn’t affect the learning curve or existing applications much while improving performance. Still, it executes more slowly than compiled languages.
  9. Scaling and maintaining PHP is a complicated endeavor.
  10. Context matters a great deal in dynamically typed languages, so tracking down errors gets harder the larger an application grows.
  11. Experienced PHP developers can mitigate this problem y planning for scalability, but there’s only so much they can do to reduce maintenance issues down the road.


Common uses of PHP

  1. PHP performs system functions, i.e., from files on a system it can create, open, read, write, and close them.
  2. PHP can handle forms, i.e., gather data from files, save data to a file, through email we can send data, return data to the user.
  3. We add, delete, and modify elements within the database through PHP.
  4. Access cookies variables and set cookies.
  5. Using PHP, we can restrict users to access some pages of your website.
  6. It can encrypt data.


 Object Oriented Programming with Server Side Scripting

Object Oriented is an approach to software development that models application around real world objects such as employees, cars, bank accounts, etc. A class defines the properties and methods of a real world object. An object is an occurrence of a class. There are three major principles of OOP are:

  1. Encapsulation: This is concerned with hiding the implementation details and only exposing the methods. It used to reduce software development complexity.
  1. Inheritance: This is concerned with the relationship between classes. The main purpose of inheritance is the re-usability.
  1. Polymorphism: This is concerned with having a single form but many different implementation ways. The main purpose of polymorphism is to simplify maintaining applications and making them more extendable.

PHP in Object oriented programming PHP is an object oriented scripting language. It supports all of the  above principles. The above principles are achieved via:

Encapsulation – using “get” and “set” methods.

Inheritance – using extends keyword.

Polymorphism – using implements keyword


Hardware and Software Requirements


Hardware requirement are not much, we just need a laptop or desktop computer. PHP 5.5+ require a  computer with at least window 2008/vista.

The computer with Pentium IV processor, RAM 2GB, hard disk 256 GB, color monitor or above is more  than enough.


To run PHP code, we need the following software on our local machine.

  1. Browser
  2. Web server (eg. Apache)
  3. PHP (interpreter)
  4. MySQL Database (it is optional)


Basics of PHP:

Setting up the environment

To run PHP a web development is needed. This needs a PHP compatible web server and interpreter.  Package like WAMP, LAMP, and XAMPP etc. can be used which includes a web server.

Writing the code and running the script

PHP scripts are plain text. A PHP script begins with <?php and ends with ?>. The PHP code is saved with  extension. PHP and is saved in the root directory of web server.


Basic PHP Syntax

A PHP script can be placed anywhere in the document. A PHP script starts with <?php and ends with ?>:


// PHP code goes here 



⮚ The default file extension for PHP files is “.php”.

⮚ A PHP file normally contains HTML tags, and some PHP scripting code.

⮚ Below, we have an example of a simple PHP file, with a PHP script that uses a built-in PHP  function “echo” to output the text “Hello World!” on a web page:


Note: PHP statements end with a semicolon (;).


PHP Case Sensitivity

In PHP, keywords (e.g. if, else, while, echo, etc.), classes, functions, and user-defined functions are not  case-sensitive.

In the example below, all three echo statements below are equal and legal:



Comments in PHP

Comments are used to make code more readable. There are two types of comments –single line and multi line comments. A single line comments starts with // while multi-line comment begins with /* and end  with */.


Loosely typed language: PHP is a loosely typed language, it means PHP automatically converts the  variable to its correct data type.

PHP Variables

A variable can have a short name (like x and y) or a more descriptive name (age, carname,


Rules for PHP variables:

∙ A variable starts with the $ sign, followed by the name of the variable

∙ A variable name must start with a letter or the underscore character

∙ A variable name cannot start with a number

∙ A variable name can only contain alphanumeric characters and underscores (A-z, 0-9, and _ )

∙ Variable names are case-sensitive ($age and $AGE are two different variables)


PHP Variable: Declaring string, integer, and float

Let’s see the example to store string, integer, and float values in PHP variables.



PHP Variable Scope

The scope of a variable is defined as its range in the program under which it can be accessed. In other  words, “The scope of a variable is the portion of the program within which it is defined and can be  accessed.”

PHP has three types of variable scopes:

  1. Local variable
  2. Global variable
  3. Static variable
Local variable

The variables that are declared within a function are called local variables for that function. These local  variables have their scope only in that particular function in which they are declared. This means that  these variables cannot be accessed outside the function, as they have local scope. A variable declaration outside the function with the same name is completely different from the variable  declared inside the function. Let’s understand the local variables with the help of an example:

Global variable

The global variables are the variables that are declared outside the function. These variables can be  accessed anywhere in the program. To access the global variable within a function, use the GLOBAL  keyword before the variable. However, these variables can be directly accessed or used outside the  function without any keyword. Therefore there is no need to use any keyword to access a global variable  outside the function.

Let’s understand the global variables with the help of an example:



Basic Programming in PHP

PHP echo and print Statements

We frequently use the echo statement to display the output. There are two basic ways to get the output  in PHP:

o echo

o print

echo and print are language constructs, and they never behave like a function. Therefore, there is no  requirement for parentheses. However, both the statements can be used with or without parentheses.  We can use these statements to output variables or strings.



Difference between echo and print


o echo is a statement, which is used to display the output.

o echo can be used with or without parentheses.

o echo does not return any value.

o We can pass multiple strings separated by comma (,) in echo.

o echo is faster than print statement.


o print is also a statement, used as an alternative to echo at many times to display the output.

o print can be used with or without parentheses.

o print always returns an integer value, which is 1.

o Using print, we cannot pass multiple arguments.

o print is slower than echo statement.


PHP Data Types

Variables can store data of different types, and different data types can do different things. PHP  supports the following data types:

  1. String
  2. Integer
  3. Float (floating point numbers – also called double)
  4. Boolean
  5. Array
  6. Object
  7. NULL
  8. Resource

PHP Data Types: Compound Types

It can hold multiple values. There are 2 compound data types in PHP.

  1. array
  2. object

PHP Data Types: Special Types

There are 2 special data types in PHP.

  1. resource
  2. NULL

PHP Boolean

Booleans are the simplest data type works like switch. It holds only two values: TRUE (1) or FALSE (0). It is  often used with conditional statements. If the condition is correct, it returns TRUE otherwise FALSE.




PHP Integer

Integer means numeric data with a negative or positive sign. It holds only whole numbers, i.e., numbers  without fractional part or decimal points.

Rules for integer:

o An integer can be either positive or negative.

o An integer must not contain decimal point.

o Integer can be decimal (base 10), octal (base 8), or hexadecimal (base 16).

o The range of an integer must be lie between 2,147,483,648 and 2,147,483,647 i.e., -2^31 to 2^31.




PHP Float

A floating-point number is a number with a decimal point. Unlike integer, it can hold numbers with a  fractional or decimal point, including a negative or positive sign.




PHP String

A string is a non-numeric data type. It holds letters or any alphabets, numbers, and even special characters. String values must be enclosed either within single quotes or in double quotes. But both are treated  differently. To clarify this, see the example below:




PHP Array

An array is a compound data type. It can store multiple values of same data type in a single variable.




PHP object

Objects are the instances of user-defined classes that can store both values and functions. They must be  explicitly declared.




PHP Resource

Resources are not the exact data type in PHP. Basically, these are used to store some function calls or  references to external PHP resources.

For example – a database call. It is an external resource. This is an advanced topic of PHP, so we will discuss it later in detail with examples.


PHP Null

Null is a special data type that has only one value: NULL. There is a convention of writing it in capital letters  as it is case sensitive.

The special type of data type NULL defined a variable with no value.



PHP Operators

PHP Operator is a symbol i.e used to perform operations on operands. In simple words, operators are used  to perform operations on variables or values. For example:

$num=10+20; //+ is the operator and 10,20 are operands

In the above example, + is the binary + operator, 10 and 20 are operands and $num is variable. PHP Operators can be categorized in following forms:

  1. Arithmetic Operators
  2. Assignment Operators
  3. Bitwise Operators
  4. Comparison Operators
  5. Incrementing/Decrementing Operators
  6. Logical Operators
  7. String Operators
  8. Array Operators
  9. Type Operators
  10. Execution Operators


Arithmetic Operators

The PHP arithmetic operators are used to perform common arithmetic operations such as addition,  subtraction, etc. with numeric values.

Assignment Operators

The assignment operators are used to assign value to different variables. The basic assignment operator  is “=”.

Bitwise Operators

The bitwise operators are used to perform bit-level operations on operands. These operators allow the evaluation and manipulation of specific bits within the integer.


Comparison Operators

Comparison operators allow comparing two values, such as number or string. Below the list of comparison  operators are given:

Incrementing/Decrementing Operators

The increment and decrement operators are used to increase and decrease the value of a variable.


Logical Operators

The logical operators are used to perform bit-level operations on operands. These operators allow the  evaluation and manipulation of specific bits within the integer.

PHP Form Handling

We can create and use forms in PHP. To get form data, we need to use PHP super global $_GET and  $_POST. The form request may be get or post. To retrieve data from get request, we need to use $_GET,  for post request $_POST.

PHP Get Form

Get request is the default form request. The data passed through get request is visible on the URL browser  so it is not secured. You can send limited amount of data through get request.

Let’s see a simple example to receive data from get request in PHP.

File: form1.html



File: welcome.php



PHP Post Form

Post request is widely used to submit form that have large amount of data such as file upload, image  upload, login form, registration form etc.

The data passed through post request is not visible on the URL browser so it is secured. You can send large  amount of data through post request.  

Let’s see a simple example to receive data from post request in PHP.

File: form1.html



File: login.php



Difference between GET method and Post method

S.N. GET Method S.N. POST Method
1 Only limited amount of data can be sent  because is sent in header. 1 Large amount of data can be sent because  data is sent in body.
2 GET request is not secured because data is  exposed in URL bar. 2 POST request is secured because data is not  exposed in URL bar.
3 GET request can be bookmarked. 3 POST request cannot be bookmarked.
4 GET is essentially used for fetching the  information. 4 The purpose of POST method is to update  the data.
5 It can be cached. 5 It cannot be cached.
6 GET method is the default method if the  method is not specified in the form. 6 POST method must be specified in the form.  It is not default method.


PHP Programs
  1. Write a php code to enter your name and display it.



  1. Write a php code to display the factorial of a number given by user.



  1. Write a php code to display all even numbers up to 50.



  1. Write a PHP code to display the simple interest.



Database Connectivity

Database: To organize the data in systematic and manageable form, the database is required. The  database is the system where data and information are stored and organized systematically.  ⮚ The stored data can be retrieved easily when required.

⮚ Data are stored in tabular form.

⮚ The number of columns and rows forms the table.

The column of the table is known as a field that has a unique field name and the row of the table is known  as records which represent individual information. Each table has a unique field known as a primary key.  Each of the records of the primary field is different which make distinct from other records for  identification.

MySQL is the most popular database system used with PHP. With PHP, we can connect to and manipulate  MYSQL databases. It is a database system used on the web that runs on a server. It can be used for  organized databases for both small and large applications. It is comparatively more fast, reliable, and easy  to use than other databases. It uses standard SQL and compiles on a number of platforms.

Basic Concept of Communication System 

A communication system is a set of interconnected components or devices that facilitate the transfer of information from one point to another. The fundamental purpose of a communication system is to convey meaningful data or messages from a source to a destination. Telephone, radio and television are the main and popular media of telecommunication.

Communication System Block Diagram

Information Source:

❖What it is: The starting point of communication.

❖Example: Your friend sharing a funny story with you.

❖In simple terms: Where the message or story originates.



❖What it is: Converts the message into a suitable form for sending.

❖Example: Your friend speaking the words of the funny story.

❖In simple terms: Changes the message so it can be sent effectively.



❖What it is: The pathway through which the message travels.

❖Example: The air carrying the sound waves of your friend’s voice.

❖In simple terms: The route the message takes to reach you.



❖What it is: Grabs the message and turns it back into something understandable.

❖Example: You listening to your friend’s words and understanding the story.

❖In simple terms: Catches and makes sense of the message.



❖What it is: Unwanted disturbances that can mess up the message.

❖Example: Background chatter making it hard to hear your friend’s story.

❖In simple terms: Anything that makes it difficult to understand the message.


Use of Information:

❖What it is: Putting the received message to some purpose.

❖Example: Laughing at the punchline of your friend’s funny story.

❖In simple terms: Doing something with the information you received.


Data Transmission

Data may be transferred from one device to another by means of some communication media. The  electromagnetic or light waves that transfer data from one device to another device in encoded form are  called signals. Data transmissions across the network can occur in two forms i.e.:

  1. Analog signal
  2. Digital signal

Analog Signal:

The transfer of data in the form of electrical signals or continuous waves is called analog signal or analog  data transmission. An analog signal is measured in volts and its frequency is in hertz (Hz).

Digital Signal:

The transfer of data in the form of digit is called digital signal or digital data transmission. Digital signals  consist of binary digits 0 & 1. Electrical pulses are used to represent binary digits. Data transmission  between computers is in the form of digital signals.



Modulation means to change. It is the process of changing or encoding the carrier wave at certain amplitude (height) and  frequency (timing).


The process of changing some characteristics (amplitude, frequency or phase) of a carrier wave in  accordance with the intensity of the signal is known as modulation.

There are three types of modulation:

  1. Amplitude Modulation (AM): Amplitude modulation is an increase or decrease of the carrier voltage (ec), will all other factors remaining constant.
  2. Frequency Modulation (FM): Frequency modulation is a change in the carrier frequency (fc) with all other factors remaining constant.
  3. Phase Modulation (PM): Phase modulation is a change in the carrier phase angle (θ). The phase angle cannot change without also affecting a change in frequency. Therefore, phase modulation is in reality a second form of frequency modulation.


Elements of Data communication System

Data communication is the process of exchanging data among the computing devices. Data may be in  different form like file, text, image, sound etc. These data are transmitted between a source and a  destination. Source device is responsible for generating data and destination device is responsible for  receiving the data generated by source. Communication like, email, IRC, VOIP etc. are examples of data  communication. Data communication is the transmission of electronic from one computing device to  another. The data communication comprises of following elements:

  1. Sender (Source)
  2. Medium
  3. Receiver
  4. Data
  5. Protocol
  6. Encoder
  7. Decoder
  1. Sender (Source): It is the device that generates and sends that message.
  2. Medium: It is the channel or physical path through which the message is carried from the sender to the receiver. The medium can be wired like twisted pair wire, coaxial cable, fiber-optic cable or wireless like laser, radio waves, and microwaves.
  3. Receiver (Sink): It is the device that receives the message.
  4. Data: It is the information or data to be communicated. It can consist of text, numbers, pictures, sound or video or any combination of these.
  5. Protocol: It is a set of rules that govern the communication between the devices. Both the sender and the receiver follow same protocols to communicate with each other. The data communication takes place between two devices connected together either by wired or  wireless media. The sender device generates the data message and send it through the  communication channel using some protocol. After the message is sent the receiver receives the  message using the similar protocol.


  1. Encoder: The computer works with digital signals. The communicational channels usually use analog signals. Therefore, to send data through a communication channel, the digital signals are encoded into analog signals or into a form which can be transmitted through transmission  medium. This is called encoding. The device that carries out this function is called encoder.
  2. Decoder: The Computer works with digital signals. The communication channels usually use analog signals. Therefore, to receive data from a communication channel, the coded analog signals or any other encoded form is converted back to digital signals. This is called decoding. The device  that carries out this function is called decoder.


Mode of Communication

Mode of communication normally refers to the ways in which communication takes place or data gets  transmitted between source and destination nodes. Modes of data transmission direct the direction,  mechanism of data flow between devices.

  1. Simplex Communication
  2.  Duplex Communication

          a. Half Duplex

          b. Full Duplex

  1. Simplex Communication: 

In this type of communication data transmission takes place only in one direction. It is also called a  unidirectional communication mode. Radio, Television, Newspaper and keyboard to CPU Communication are some of the most common  example of simplex communication.


⮚ Data are transmitted in only one direction.

⮚ The sender sends data and receiver receives only.

⮚ There is not bidirectional communication.

⮚ Listeners cannot reply immediately.

⮚ Radio and television broadcast are its examples.


  1. Duplex Communication: 

In duplex communication mode data transmission is possible from both directions. The receiver can  immediately respond to the sender. The duplex communication can be categorized into two groups.

Half Duplex: 

In this type of communication mode data can be transmitted in both directions, but only in one direction  at a time. Both sender and receiver cannot transfer the data at a time. While sending data it cannot  receive it and while receiving data it cannot send.


⮚ Data are transmitted in both direction but single direction at one time.

⮚ Receiving end acts as mere listener while sender sends data and vice versa.

⮚ The communication is slower.

⮚ Walkie Talkie used by the police man is the best example of half-duplex communication mode.

Full Duplex

Full Duplex communications allows data to flow the information at the same time. Speaking on telephone  of full Duplex communication mode in which both the sender and receiver can speak simultaneously.  Bidirectional communication at the same time is called full duplex communication mode.


⮚ Data are transmitted in both direction at the same time.

⮚ When one end sends data other end can receive as well as send data.

⮚ Communication is faster.

⮚ Telephone is an example of full duplex mode.


Difference between simple, half and full duplex

S.N. Simple Half Duplex Full Duplex
1. It is a uni-directional communication. It is a two way directional communication but one at a time. It is a two way directional communication simultaneously.
2. Sender can send the data but can’t receive the data in it. Sender can send the data and also can receive the data but one at time in it. Sender can send the data and also can receive the data simultaneously in it.
3. It provides less performance than half duplex and full duplex. It provides less performance than full duplex. It provides better performance than simple and half duplex mode.
4. Examples: radio, newspaper Examples: Walky-talky and wireless handset Example: smart phone and landline phones.


Computer Network:

⮚ Computer Network is defined as the collection of two or more autonomous computers which are interconnected  together for sharing resources with the help of transmission media and set of protocols.

Services provided by the computer network:

⮚ Data sharing

⮚ Print service

⮚ File service

⮚ Database service

⮚ Application service


Advantages of Computer Network:

  1. Sharing resources: Software and hardware resources such as processor, storage devices, printers, scanner, etc. can be shared among us using computer network. It helps to minimize the operational cost of an organization.
  2. Saving Cost: Sharing of hardware and software resource avoids duplication, helps in optimal utilization of all types of resource like printer, disks, database etc.
  3. Faster and cheaper communication: Communication in modern days has become very faster and cheaper to send information to a long distance through network.
  4. Centralized control: All network resources such as computers, printer file, database, etc can be managed and controlled by a central connecting computer also known as the server.
  5. Enterprises and chain organization developed: One office or head of the organization can easily visualize and monitor offices and staffs geographically located in different places through videoconference, CC camera etc.
  6. Backup and recovery: Server is used to keep data as backup. It maintains backup of all individual computer information.
  7. Remote and mobile access: A remote user can access resources from the distance using computer network.

Disadvantages of Computer Network:

  1. Expensive: In order to install computer network, we require some extra cost to purchase networking devices such as hubs, switch, cables, etc.
  2. Security problems: Network security is the most challenging job for network administrator in order to protect network resources from authorized users and physical destructions.
  3. Needs technical person: It is very difficult to install and operate good computer network without the help of technical person.


Types of Computer Network

On the basis of size computer networks can be classified into three categories:

  1. PAN (Personal Area Network): The computer network formed around a person is called Personal Area Network (PAN).

⮚ It is personal device network within a limited area.

⮚ It consists of a computer, mobile, Personal Digital Assistant (PDA). It can be used for  communication among these personal devices for connecting to a digital network and the  internet.


  1. It can be relatively secure and safe.
  2. It offers short-range up to ten meters.


  1. It may establish a bad connection to other network
  2. It is limited within shorter distances.
  1. Local Area Network (LAN): A LAN is privately owned small size network. It spans only in small geographical area such as within a room, office, buildings or up to few kilometers (2 to 3 Km). It connects the network resources such as computers, faxes, printers and various networking  devices.

Advantages of LAN

  1. It is cheaper to establish.
  2. Data transmission is faster than MAN and WAN.
  3. It has higher security to resources of the network
  4. It is easier to establish, manages of the network and operate

Disadvantages of LAN

  1. It is limited only to a small area.
  2. It can connect less number of computers comparatively.
  3. Cannot be used as distributed network.
  1. Metropolitan Area Network (MAN): A MAN can be either public or privately owned network. Its size is bigger than LAN and smaller than WAN. It spans within one metropolitan city or larger geographical area. It can connect large number of computers and heterogeneous multiple LANs within a city  maximum, up to 100Km.

Advantages of MAN

  1. It covers larger geographical area than LAN.
  2. It can connect large number of computer than LAN.
  3. We can use guided as well as unguided type of transmission media.

Disadvantages of MAN

  1. It is expensive to set up then LAN.
  2. Transmission speed slower compared to LAN.
  3. It is complex to establish, manage and provides security.
  1. Wide Area Network (WAN): A WAN is basically public type heterogeneous network. It is the largest sized network and connects millions of computers, thousands of LANs, hundreds of MANs around the countries, continents and even the whole world.

Advantage of WAN

  1. It covers larger geographical area than LAN and MAN.
  2. It can connect large number of computer compared to LAN and MAN.
  3. Using WAN communication can be done over a large distance.

Disadvantage of WAN

  1. It is expensive to establish, manage and operate.
  2. It is the slowest type of network compared to that of LAN and MAN.
  3. Highly qualified manpower are required to establish and run these type of network.


Differentiate between LAN and WAN

S.N. Local Area Network (LAN) S.N. Wide Area Network (WAN)
1. Area covered within a local site. 1. Distance up to thousands of K.M.
2. Higher data transfer rates (10 Mbps to 1Gbps  even more). 2. Data transfer rate is less
3. It has low error rates. 3. It has higher error rates.
4. It uses simple protocol, low cost devices and  low cost installation. 4. It uses complex protocols, expensive  devices and high cost installation.
5. It can support limited number of hosts. 5. It can support large number of hosts.
6. Eg. Star, cellular topologies etc. 6. Eg. Internet and intranet


Comparison of LAN, MAN and WAN

1. The computer network  limited over small geographical area such as  building or room. The computer network  spread over the city or  country is known as MAN . The computer network  spread over the world is  known as WAN.
2. It is owned by an private organization. It can be owned by private  or public organizations. There is no single ownership  or WAN .
3. The bandwidth of LAN is  high. i.e. data transmission  rate. The data transmission rate  is slower in comparison to  LAN. The data transmission rate is  slowest in comparison to  LAN and MAN.
4. There is less congestion in  LAN. There is more congestion in  MAN. There is more congestion in  comparison to LAN and  WAN.
5. It is easy to design and  maintain. It’s design and maintenance  is difficult than LAN. It’s design and maintenance  is difficult than LAN and  MAN.
6. There is more fault tolerance. There is less fault tolerance. There is also less fault  tolerance.
7. It is used in school, college,  hospital…etc. It is used in city, towns. It is used for countries,  continent and globe.
8. Transmission channels are  normally twisted pair cables. Transmission channel are  fiber optics, coax cable. Communication channel  ranges from fiber optics  cables to communication  satellites.
9. It Stands for Local Area  Network It stands of Wide Area  Network It stands for Metropolitan  Area Network.


Transmission media:

A transmission media is defined as the means of communication between two networking devices that  helps to transfer data from sender to receiver and vice versa.

⮚ Transmission channel is the path through which data are transmitted from source to destination.

⮚ The path through which data transmit from source to destination is known as communication  media.

Transmission media is broadly classified into two groups.

  1. Bound (guided)/ Wired media
  2. Unbound ( unguided) / Wireless media

1) Bound (guided)/ Wired media

⮚ Guided Media are those communication channels that directly link with each other through cables or other physical media.

⮚ Data are transmitted in the closed path through transmission media.

⮚ Data gets transmitted through wires or cables in guided media.

⮚ In guided media, there is a direct connection between source and destination nodes.

⮚ Guided media has high bandwidth, low cost, and high security.

⮚ Data transmission is faster than wireless.

⮚ The most commonly used guided media are Twisted Pair cable, Coaxial Cable and Fiber Optics.


2) Unbound ( unguided) / Wireless media

⮚ The data transmitted in this medium is through electromagnetic waves so that any physical wire or cable is not required for the transmission.

⮚ Unguided media transmission is bounded by geographical areas.

⮚ Different types of unguided media are: Microwave, Radio wave, satellite communication, Bluetooth, Infrared, Wi-Fi, Li-Fi.


Difference between Guided Transmission and Unguided Transmission Medium

S.N. Guided Transmission Medium S.N. Unguided Transmission Medium
1. Signal is directed and contained by the  physical limits of the medium. 1. It has no physical medium for the transmission of electromagnetic signals.
2. It is called wired communication or  bounded transmission media. 2. It is called wireless communication or  unbounded transmission media.
3. The signal energy propagates through  wires in guided media. 3. The signal energy propagates through air in  unguided media.
4. It types are twisted pair cable, coaxial  cable and fiber optic cable. 4. It types are radio wave, microwave and  infrared.
5. Examples: Twisted pair cable, coaxial cable  and fiber optic cables. 5. Examples: Microwave or radio links and  infrared light.


  1. Wired or Guided Media or Bound Transmission Media:

The transmission of data and information  from source to destination by using physical medium like wires are called bounded transmission  media. Its types are as follows.

1) Twisted pair cable

i) Shielded Twisted pair cable (STP)

ii) Unshielded Twisted pair cable (UTP)

2) Coaxial Cable:

2.1. Thinnet

2.2. Thicknet

3) Fiber optics


  1. Twisted pair cable:

A pair of copper wires is twisted to each other in a helical path making the same  structure as a DNA molecule.

– The reason for twisting is to reduce electrical interference.

– It is the cheapest and easily available wire.

– It is mostly used in telephone systems.


  1. It is cheaper than other cables.
  2. It is light and thin. So, it is flexible for LAN.
  3. It can travel data in short distance with higher bandwidth.


  1. It is only used for short distance transmission.
  2. It can be affected by electrical and magnetic field.
  3. It is slower type of transmission media compared to other cables.


Features of STP Cable:

» Better performance and high data transfer rate.

» Eliminates cross talk

» Faster than UTP

» More expensive



▪ Less expensive.

▪ Easy to install.

▪ High speed capacity.

▪ Susceptible to external interference.

▪ Lower capacity and performance than STP.

▪ Short distance transmission.


         Difference between UTP and STP

1. Electromagnetic interference and noise is more  in UTP 1. STP cable reduce electrical noise within the  cable and from outside of the cable.
2. It offers speed or throughput of about 10 to 1000  Mbps. 2. It offers speed or throughput of about 10 to  100 Mbps.
3. It offers maximum cable length of about 100  meters. 3. It supports maximum segment of length  about 100 meters.
4. UTP is widely used for data transmission within  short distance and is very popular for home  network connecting. 4. STP is mainly used for connection of  enterprises over a long distance.
5. The cost of UTP is less when compared to that of  STP. 5. STP is costlier than UTP.


2. Coaxial Cable:

Coaxial cable is a type of copper cable specially built with a metal shield and other components  engineered to block signal interference. It is primarily used by cable TV companies to connect their  satellite antenna facilities to customer homes and businesses.

Coaxial cable contains two conductors inner and outer, which are separated by an insulator. These two  conductors lies parallel to each other. The inner conductor is made up of copper wire which is covered by an inner insulator. The inner insulator is again covered by outer conductor or metal foil. Outer metal  wrapping is used as a protection against noise and as the second conductor which completes the circuit.  The outer conductor is covered with an insulating cover.


  1. It is faster and reliable than twisted pair cable.
  2. It can transfer data over medium range of distance.


  1. It is not appropriate for relatively larger distance.
  2. It is expensive than twisted pair cable.
  3. It is rarely used in computer network.

Coaxial cable is of two types: 

(a) Baseband transmission (Thin net): It is defined as the process of transmitting a single signal at  high speed.

(b) Broadband transmission (Thick net): It is defined as the process of transmitting multiple signals  simultaneously.


3. Fiber Optics:

It is the most advanced media in communication, which uses light rather than electricity to transmit  information. Optical fiber is very thin media, which is measured in microns and is very hard to identify  with our naked eye. They’re designed for long-distance, high-performance data networking, and  telecommunications. Fiber optic cables support much of the world’s internet, cable television, and  telephone systems.


  1. Data are transmitted in the form of light signals.
  2. It is made up of glasses or plastics cover with fiber to protect.
  3. It is difficult to install.
  4. It has high bandwidth.
  5. Data can transfer longer and faster than twisted pair and coax cable.


  1. It has higher bandwidth that means it can handle large volume of data.
  2. This medium can be used for long distance transmission.
  3. It is the most secured and error free transmission medium.


  1. It is one of the expensive type of transmission media.
  2. It is not used for short distance transmission.
  3. Highly qualified and technical manpower are required to operate on fiber optics.
  4. Difficult to install and Fragile in nature.


  1. Wireless or Unguided Media or Unbound Transmission Media:

Unbound transmission is also called wireless or unguided media. If there is no physical connectors (wires) between the two communicating device is called wireless transmission media. Its types are as  follows.

  1. Radio Wave
  2. Microwave
  3. Infrared
  4. Satellite Communication:

  1. Radio wave:

Radio wave are the signals ranging frequency in between 3 KHz and 1 GHz. When the antenna transmits the radio wave, they are propagated in all directions. Due to this the  sending and receiving antenna doesn’t need to be in line of sight position. Antenna is responsible for  converting outgoing data packets into radio waves and vice-versa.


⮚ It is wireless communication technology that transmits voice or data over the air using a lower  frequency band than microwaves.

⮚ The signal is travel in up and down manner so that it can reach any place until the strength of  waves falls.

⮚ AM and FM radios and cordless phones use radio waves for transmission.

  1. Microwave:

Microwave, in contrast, have been used in data communications for a long time. They have a higher  frequency than radio wave and therefore, they can handle larger amounts of data. There are, of course,  problems with microwaves attenuation and environmental interference.

⮚ Microwave transmission is the line of sight transmission.

⮚ The transmit station must be in visible contact with the receive station.

⮚ The microwave is unidirectional.

⮚ This sets the limit on the distance between stations depending on the local geography.

⮚ The microwave is another type of electromagnetic waves that have a frequency range of 1 GHz to  300 GHz.

⮚ In this transmission, whenever the signals are transmitted through an antenna, proper  alignment of sending antenna and receiving antenna should be maintained.

  1. Infrared:

Infrared offers a great unbound photonic solution like fiber-optic cabling.  Infrared communications use  light. So, they are not bound by the limitations of electricity. They are normally used for short range  communication such as in communication of remote and TV, AC etc.


Satellite Transmission:

These are the artificial satellites which are placed in the space for the purpose of communication  between different antennas available of on the earth. These artificial satellites facilitate the transmission  of signals between stations of the earth. They relays and amplifies radio telecommunication by creating  communication channel between source transmitter and destination transmitter.


Transmission Impairments Terminologies 

(Jitter, Singing, Echo, Crosstalk, Distortion, Noise, Bandwidth and Number of receivers)


⮚ When we make a call over internet with anyone and suddenly line drops and their voice starts  breaking up, it’s called jitter.

⮚ Jitter is defined as a variation in the delay of received packets.

⮚ Jitter is when there is a time delay in the sending of these data packets over your network  connection.


⮚ Singing is the result of sustained oscillations due to positive feedback in telephone amplifiers  or amplifying circuits.

⮚ Singing may be regarded as echo that is completely out of control. This can occur at the  frequency at which the circuit is resonant.


⮚ Echo in telephone systems is the return of a talker’s voice. It is most apparent to the talker himself  or herself. Secondarily, it can also be an annoyance to the listener.

⮚ Echo is a major annoyance to the telephone user. It affects the talker more than the listener. Two  factors determine the degree of annoyance of echo: its loudness and its length of delay.


⮚ Crosstalk is a disturbance caused by the electric or magnetic fields of one telecommunication  signal affecting a signal in an adjacent circuit.

⮚ It is an effect of a wire on another. One wire acts as a sending antenna and the transmission  medium acts as the receiving antenna. Just like in telephone system, it is a common experience  to hear conversation of other people in the background. This is known as cross talk.


⮚ Distortion is the change in the form or shape of the signal. Signals are made up of different  frequencies are composite signals.

⮚ Distortion occurs in these composite signals. Any change in a signal that alters the basic  waveform or the relationship between various frequency components is called distortion. It is  usually a degradation of the signal.


⮚ Noise is another impairment in data communication. During data communication there are some random or unwanted signals mix  up with the original signal is called noise.

⮚ Noises can corrupt the signals in many ways along with the distortion introduced by the  transmission media.


⮚ Bandwidth is the amount of data transmitted through the transmission channel at certain  period of time. High bandwidth means higher bits of data are transmitted and low bandwidth  means less bits of data are transmitted through the communication channel.

⮚ The bandwidth of analog device is measured in Hertz (Hz) and bandwidth of digital device is  measured in bps (bits per second). It is also known as data holding capacity of transmission  channel.


⮚ Receiver, in electronics, any of various devices that accept signals, such as radio waves, and  convert them (frequently with amplification) into a useful form. Examples are telephone  receivers, which transform electrical impulses into audio signals, and radio or television  receivers, which accept electromagnetic waves and convert them into sound or television  pictures.


Network architecture:

Network architecture refers to the various services provided by the network and it also deals with how  data is transmitted from one computer to others.

  1. Client server network: An arrangement of computers to resource sharing and communicate each other through a central device (server) to all workstations (clients) is called client server architecture. One or more computers in the network act as server which provides services to other computers which are called clients.

⮚ The server is a high capacity high speed computer with a large memory.

⮚ Server contains the network operating system.

⮚ The central server manages, organize, and coordinate all network clients on the network.

⮚ The most common service is provided by different servers are file services, print services,

⮚ Message services and database services.


  1. Centralized administration is possible through this network.
  2. High security can be provided by suing appropriate server.
  3. It is appropriate for large organization.
  4. Data recovery and backup process is easier.


  1. If server fails whole network is affected.
  2. It is expensive due to use of dedicated server.
  3. It is complex to establish and manage.
  4. Experienced administrator is required to operate.
  1. Peer-peer network: In peer-to-peer architecture computers are connected individually in pair (one to-one connection). A peer-to-peer network is the type of network in which all computers in the network act as both a client and a server i.e. all computers can both request and provide services.

⮚ Each workstations act as both a client and a server.

⮚ There is no central repository for information and no central server to maintain.

⮚ Peer to peer network are generally simpler and less expensive.

⮚ A peer to peer network is also known as a distributed network.

⮚ Peer to peer computing or networking is a distributed application architecture that partitions  task or workstations between peers.

⮚ Peers are equally privileged and equal participants in the application.

⮚ Each node shares its sources with other nodes in the network.


  1. It is simple, cheap and easier to set up.
  2. Since there is no dedicated server, user can manage their own server.
  3. Failure of a computer in a network doesn’t effect the other computer in a network.


  1. Data security is very poor in this type of architecture.
  2. Data recovery and backup is difficult.
  3. It is not appropriate for large scale organization.
  4. Network administration is difficult it without dedicated Server.


Difference between Client Server and Peer to peer

Client Server Peer to peer
1. It is also known as centralized or server based  network. 1. It is also known as distributed network.
2. It has central server computer. 2. There is no central server computer.
3. The central server manages, organize, and  coordinate all network clients on the network. 3. Peers are equally privileged and equal  participants in the application.
4. Client server network are more expensive. 4. Peer to peer network are generally  simpler and less expensive.
5. It has high security. 5. It is less security.
6. If server crashes there is a chance of data loss. 6. Data and information is shared around  the network, so less chance of data loss.
7. Example, Google server, Yahoo server and  Bank etc. 7. Example One to one computer and  Bluetooth connectivity etc.


Network or LAN topology and its types

Network topology refers to the physical layout of the network. It shows the geographical representation  of all the links and linking devices, also called nodes. It is the shaped of Network.  The main objectives of the network topology is to find out the most economical and efficient way of  transmission channel.

Its types are as:

  1. Bus Topology: Computers are connected to a single continuous cable that is called ‘bus’. It acts as backbone. It is based on client server network architecture.


  1. It is simple and easy to setup and extend the network.
  2. It required less cable.
  3. If any computer in the network downs, then it does not affect the whole network.
  4. We can easily connect and disconnect any number of computers in the bus.


  1. Data traffic is very high in bus.
  2. If there is problem in main cable then entire network goes down.
  3. It is very difficult to find out the fault in the bus.
  1. Star Topology: Computers in the network are connected to each other with the help of central connecting device hub or switch or server. It is based on client server architecture. It is the most popular and widely used topology for LAN.


– It is simple, reliable and easy to set up and re-configuration.

– It is flexible to connect new computer and remove existing computer in the network.

– It is very easy to find out fault.

– If any computer in the network goes down, then other computers can continue their functions.


– It requires very large amount of cables.

– It is expensive topology.

– If there is any problem in central device hub or switch then the entire network will be down.

– The data traffic is high in central device hub.

  1. Ring Topology: Computers are interconnected to each other by making a closed circular structure that means each computer is connected to other two adjacent computer in either network architecture.


– It is simple and inexpensive topology.

– There is less chance of data collision because of unidirectional data transmission.

– There is no server so each computer has equal access facilities to the resources.

– Its performance is better than bus topology for small size network.


– It is not flexible topology so it is difficult for adding and removing new nodes.

– It is not suitable for large size network.

– If there is problem in any computer or connection then the entire network goes down.

– It is very difficult to find out the errors in the network.

  1.  Mesh Topology: Every computer in the network has point to point connection to all other computers by using multiport connector. It is also based on peer to peer architecture.


– It is fastest and most reliable topology.

– Failure in any computer or transmission media does not affect the rest of the network.

– There is less amount of data traffic due to multiple paths.


– It is very much complex and most expensive topology.

– It is difficult to find an error in the network.

– It is difficult to add and remove nodes in the network so it is not flexible.

– It requires maximum amount of cables and multiport connectors.

  1. Tree Topology: Tree topology is the extension of bus or star topology. Data can flow from top to bottom and vice versa.


– It is easy to manage network as per our needs.

– It is very flexible so we can add and remove any number of nodes.

– It is easier to find the fault nodes or hubs in the network.


– The failure of root node will cause the failure of entire network.

– It is expensive because it needs large number of cable and network device.

– The data traffic is high at root nodes.

  1. Hybrid topology: If two or more topologies are combined together then it is called hybrid topology. So it is very difficult to design and to implement the hybrid topology. It is expensive too.


⮚ Reliable

⮚ Scalable

⮚ Flexible

⮚ Effective


⮚ Complexity of design

⮚ Costly connecting devices

⮚ Costly infrastructure


OSI (Open System Interconnection) reference model

It is based on a proposal developed by the international organization for standardization (ISO). The model  is called ISO OSI reference model, because it deals with connecting open system i.e. the system that are  open for communication with other system.

  1. Physical Layer: This layer concerned with transmission of bit it determines voltage level for 0 & 1. It also determines the data rate of the system. This layer involves standardized protocol dealing with electrical & signaling interface.
  2. Data Link Layer: It handles error in physical layer. This layer ensures the correct delivery of frame to the destination address. It consists of 2 parts or 2 sub-layers. i.e.

i. Logical Link Control

ii. Media Access Control

  1. Network Layer: This layer is concerned with transmission of packet. Network layer protocol chooses the best path to send a package called routing. Two protocols are widely used in network layer.

i. X.25 Protocol

ii. Internet Protocol

  1. Transport Layer: It provides the mechanism for the exchange of data between end systems. It ensures that the data received is in fact in order. Following jobs are performed by this layer.

i. Port Addressing

ii. Segmentation & Reassemble

iii. Connection Control

  1. Session Layer: It is responsible for requesting logical connection to be established for communication process. This logical connection is termed as session. It also provides data synchronization between two communication terminals.
  2. Presentation layer: This layer translates format data to adapt to the needs of the application layer & nodes at both receiving & sending end of communication process. It handles data communication, formatting, encryption, decryption, etc.
  3. Application Layer: It is the top-most layer of OSI model & provides user access to the network. It provides services that support user application, such as database access, email & file transfer, etc.


Network Connecting devices:

The devices of computer network which are used to connect network is called the network connecting devices. We can connect two or more networks together to create larger network. A LANs can be  connected others LANs, MANs or WAN.

  1. Network Interface Boards or Network Interface Card (NIC):

The NIC contains the electronic circuitry needed to ensure the reliable communications between  workstations and servers. The NIC is the electronic interface between the computer and the LAN cabling. The card itself uses a bus-specific edge connector to plug into the computer motherboard. On the exposed  side of the NIC, there are cabling ports that plug directly into the LAN cabling.

  1. Repeaters:

As the name implies, repeaters repeat network data. In general, repeaters operate at the electronic level  and contain no real intelligence. A repeater accepts weak signals, electrically regenerates them and then  sends the messages on their way. There are two types of repeaters: amplifiers and signal-regenerating  repeaters.

  1. Hubs:

Technically speaking, a hub is simply a multiport repeater. In addition to regenerating network data, hubs  add form and function to the layout of the LAN. In many topologies, the hub is the central component of  the network transmission media. There are three types of hubs. They are the passive hub, active hub and  intelligent hub.

  1. Bride:

It is a device, which connects different network segments and passes data with the same communication protocols. It is the connecting device between two or more hubs.

– It operates at layer 2 (Data Link Layer) of OSI Model.

– It reduces unnecessary traffic problem by controlling broadcasting.

– Bridges are more intelligent than hubs because they maintain MAC address tables in them and forward data looking on it.

  1. Router:

A router transmits information from one network to another. The router selects the best path to route a  message, based on the destination address and origin. The router can direct traffic to prevent head-on  collisions and smart enough to know when to direct traffic along back roads and shortcuts.

– Direct signal traffic efficiently.

– Route message between any two protocols.

– Route message between different topologies.

– Route message across fiber optic, coaxial, and twisted-pair cabling.

  1. Gateways:

Gateways are just like routers but much more complex and powerful than routers. They are slower than  router and expensive. A gateway has all the features of router and bridges but it can translate instruction  set on sending network into receiving network.

– Gateways make communication possible between different architecture and environments.

– Gateways having higher layer functionalities and works on multiple layer protocols.

  1. Wi-Fi:-

The term Wi-Fi suggests Wireless Fidelity. It is hardware and software devices. It is wireless technology  and network connecting device. Wi-Fi is not a technical term. The technical term of Wi-Fi is “IEEE802.11”

– It has limited range.

– Wi-Fi is used in many personal computers, video game consoles, MP3 players, smart phones, printers, digital camera, laptops computers and other devices.

– Wi-Fi is used to create wireless LAN to connect computer system.

  1. Bluetooth:

Bluetooth is a wireless technology standard for exchange data over short distance from fixed and mobile  devices. Bluetooth is used to create personal area networks (PANs) with high levels of security.

  1. Infrared (IR):

Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light and below  the red light. These wavelengths correspond to a frequency range of approximately 100 GHz to 100 THz  and include most of the thermal radiation emitted by objects near room.


Some basic terms:


The Internet is an interconnected network of thousands of networks and millions of computers linking  business, educational institutions, government agencies, and individuals together.

Uses / Application of internet

  1. Search information
  2. Email service
  3. Communication
  4. File Transfer
  5. Remote login
  6. Publishing of articles, reports, and newsletter.
  7. Online education
  8. Online shopping
  9. Entertainment.


Subnet Mask 

The subnet mask number helps to define the relationship between the host (computers, routers switches,  etc.) and the rest of the network. As the name indicates, the subnet mask is used to subdivide a network  into smaller, more manageable chunks.



A gateway is a network node that serves as an access point to another network, often involving not only  a change of addressing but also a different networking technology.


IP Address

An Internet Protocol address (IP Address) is an unique identification number assigned to each devices  connected in a network that uses Internet protocol for communication. The typical IP address looks like

IP address are expressed in decimal as above which is easier for us to remember, but computers  communicate in binary. So same IP address looks like 11011000.00011011.00111101.10001001

IP address has four sets of number separated by a period ( . ), These sets are Called Octets. IP address  perform mainly two functions. One is identification of Network and Identification of particular host in  that network.


MAC address

Media Access Control (MAC) address also known as hardware or physical address is unique number  associated with a network adapter (NIC). It is used to uniquely identify each device (node) of a network.  MAC address is usually assigned by the manufacturer of a network interface card (NIC) and are stored in  its ROM. All NIC developed contains unique MAC address. It is a 12 digit hexadecimal number (48 bit in  length) and are Written in following formats.


The first half of the address contains ID number of the adapter regulated by an Internet standards body  and other half represent the number assigned by the manufacturer. For example: 00:A0:C9:14:C8:29 The prefix 00A0C9 indicates manufactures Intel Corporation and 14C829 indicates a particular host.



An intranet is a private network that uses internet protocols, to securely share part of an organization’s  information between its employees. An intranet is a Local Area Network or Wide Area Network that uses  TCP/IP protocol but, belongs to a corporation, school, or organization.

The intranet is accessible only to the organization’s workers. If the intranet is connected the Internet,  then it is secured by a firewall to prevent unauthorized users from gaining access to it.

Advantages of an Intranet

1.Workforce productivity: Employees can easily access and share information in-between their  workgroups which enhances productivity.

2.Time: With intranets, organizations can make more information available to employees in any time.

3.Communication: Intranets can serve as powerful tools for communication within an organization.


An extranet is a private intranet that can be accessed by outside users over the secure channel. To gain  entrance to the extranet resource, an external user must log on to the networks by providing a valid  user ID and password. The extranet is a combination of the public Internet and the closed intranet.


Difference between Intranet and Internet



1. It is a private network. 1. It is a public network.
2. Intranet users are your own employees who know a lot  about the company, its organizational structure and  special terminology. 2. Internet user know much less about  your company and also care less  about it.
3. The intranet is used for everyday work inside the  company. 3. The Internet is mainly used to find  out information.
4. The intranet will have many official draft reports, project  progress reports, human resource information, and other  detailed information. 4. Internet have all types of  information based on requirements.
5. Intranet has less amount of information. 5. Internet has tremendous amount of  information.
6. Intranet can work on low and mid-bandwidth. 6. Internet requires higher bandwidth.


Network Tool

Network tools are used for supporting easier and effective network connections. Some of the network  tools are:

  1. Packet tracer: Packet Tracer is an innovative and powerful network simulator that can be used for a practice build  own network with routers, switches, wireless, and much more. It allows to experiment with network  behavior, build models and to ask “what if” questions. It is used to trace the movement of data  packets in data communication. Packet Tracer provides simulation, visualization, authoring,  assessment, and collaboration capabilities to facilitate the teaching and learning of complex  technology concepts.
  1. Remote login: Remote login allows a user terminal to connect to a host computer via a network or direct telecommunications link, and to interact with that host computer as if the user terminal were directly connected to that host computer. Remote Login is a process in which user can login into a  remote site i.e. computer, and use services that are available on the remote computer. With the help  of remote login a user can understand result of transferring result of processing from the remote  computer to the local computer.


A communication protocol is a formal description of digital message formats and the rules for exchanging  that message in between computer systems. Protocols define a set of formal rules describing how to  transmit data especially across a network.

    1. TCP/IP (Transmission Control Protocol/Internet Protocol): TCP/IP is a layered set of protocols TCP is reliable, but complex transport-layer protocol. It is stream connection-oriented and reliable transport protocol. TCP/IP is the protocol used by Internet. It adds connection-oriented and reliability features. TCP  is responsible for making sure that the data is transmitted to other end. It keeps track of what is sent, and  retransmits any data that has not reached its destination. The Internet Protocol (IP) is the principal  communication protocol used for transmitting data packets across and network using the Internet Protocol Suite. Internet exist due to TCP/IP.
    2. FTP (File Transfer Protocol): This protocol is used for transferring data between client and server over TCP/IP (Internet). Hence, it is responsible for uploading and downloading files to and from the server.
    3. UDP (User Datagram Protocol): UDP is simple, connection less, unreliable transport protocol. It performs very limited error checking. It is mainly used for transmitting multimedia data, which requires faster transmission and error checking is not used.
    4. SMTP (Simple Mail Transfer Protocol): SMTP is a standard protocol for transmitting electronic mail (email) by the internet. It is a Internet mail protocol. It is a TCP/IP protocol used to send emails.
    5. POP (Post Office Protocol): POP is also a protocol for transmitting email. It is simple but has limited functionality. It is an application layer Internet standard protocol used by clients to access e-mail from a server over a TCP/IP connection i.e. internet. POP3 (POP version 3) is used at present. POP3 is supported  by most modern webmail services such as Gmail and Yahoo Mail.
    6. HTTP (Hypertext Transfer Protocol): HTTP networking protocol for distributed, collaborative, hypermedia information systems. It is used transmitting hypertext or HTML based document. It is the foundation of data communication for the World Wide Web used by web browser to communication with  respective servers.

  1. HTTPS (Hypertext Transfer Protocol Secure): HTTPS is combination of Protocol with the SSL/TLS protocol to provide encrypted identification of a network. HTTPS connections are often used in World Wide Web for sensitive transactions. The main objective of HTTPS is to create a secure channel over an  insecure network.


Data is defined as the raw facts and figures. It could be any number, pictures, sound, alphabet, or any combination of it which do not provide clear meaning. Examples, Ram, 12, 75, etc. Here, Ram, 12, 75 does not provide clear meaning. It could mean 12 GB RAM which costs $75 or 12 years old Ram which could give 75 kg of wool in its lifetime.

Sources of Data:

  1. Primary Data: Facts and figures newly collected. Examples are observation data, questionnaire data, survey data, etc.
  2. Secondary data: Facts and figures already collected. Examples are financial statements, customer lists, sales reports, census reports, etc.

Data Processing:  

Data processing is the mechanism of converting unprocessed data into meaningful results or information.


When data are processed using a database program or software, they are converted to a meaningful result, called information. The information provides answers to “who”, “what”, “where”, and “when”  questions.

Examples: Ram, roll no 12 and he scored 75 out of 100 in a test.

Difference between Data and Information

S.N. Data S.N. Information
1 It is raw or known facts. 1 It is processed or refined data.
2 It stores the facts. 2 It presents the facts.
3 It is inactive (they exist). 3 It is active (It enables doing).
4 It is technology-based. 4 It is business-based.
5 Data is gathered from various sources. 5 Information is transformed from data
6 Data do not have a fixed format. 6 Information is normally in the form of tables, graphs,  curve lines, etc.


Flat File/ File based system:

Limitation of file-based/ Flat file system

  1. Duplication of data ( Data Redundancy)
  2. Inconsistent data.
  3. Program Data Dependence.
  4. Poor data control.
  5. Limited data sharing.
  6. Security problems.
  7. Incompatible file formats.
  8. Fixed queries
Database System:

A database system consists of a collection of interrelated data and a set of application programs to access,  update and manage the data.


It is organized form of record about some person, organization or something store under certain media. It is a collection of related information about a subject organized in a useful manner that provides a base  or foundation for procedure, such as retrieving information, drawing conclusion and make decision.

Advantage of database over flat file or file based system :

  1. Reduction of data redundancies
  2. Shared data
  3. Data independent
  4. Improved integrity
  5. Efficient data access
  6. Multiple user interface
  7. Improved security
  8. Improved backup and recovery
  9. Supports for concurrent transactions
  10. Unforeseen queries can be answered
File based system Vs Electronic Database System
S.N. File Based System S.N. Electronic Database System
1 It provide detail of the data representation and storage of data. 1 Database System gives abstract view  of data that hides details.
2 It doesn’t have a crash recovery  mechanism. 2 It provides crash recovery mechanism  using backup and other security  measures.
3 It is difficult to reduce data redundancy. 3 Data redundancy can be done easily.
4 Searching of data requires a lot of time  and effort. 4 Data can be easily searched.
5 Difficult to maintain the database. 5 Easy to maintain the database.


Database Management System (DMBS):

Database Management System is software that manages the data stored in a database. This is a collection  of software which is used to store data, records, process them and obtain desired information. Since, data  are very important to the end users, we must have a good way of managing data. A DBMS is a collection of programs that manages the database structure and controls access to the data  stored in the database. The DBMS make it possible to share the data in the database among multiple  applications or users. The DBMS stands between the database and the user.

Examples: MS-Access, Oracle, FoxPro, dBase, SQL server, MySQL, Delphi, Sybase, etc.


Architecture of DBMS

Why to Use DBMS? 
  1. To develop software application in less time.
  2. Data independence and efficient use of data.
  3. For uniform data administration.
  4. For data integrity and security.
  5. For concurrent access to data, and data recovery from crashes.
  6. To use user friendly declarative query language.

Some major database System activities are (Functions of DBMS)

  1. Adding new file to the database.
  2. Inserting data into the database.
  3. Retrieving/viewing data from the database.
  4. Updating data in existing database file.
  5. Deleting data from the database file.
  6. Removing files from the database.

   Advantages of DBMS (Features/Objectives of DBMS)

  1. Sharing data
  2. Reduced data redundancy
  3. Data backup and recovery
  4. Inconsistency avoided
  5. Data integrity
  6. Data security
  7. Data independence
  8. Multiple user interfaces
  9. Process complex query

Disadvantages of DBMS:

  1. Expensive
  2. Changing Technology
  3. Needs Technical Training
  4. Backup is Needed.


Field/ Attribute:

A field is a piece of information about an element. A field is represented by a column. Every field has got  a title called the field title.

Record (Tuple):

A record is information about an element such as a person, student, an employee, client, etc. A record  can have much information in different heading or titles.


A table is the arrangements of rows and columns. Each table must have unique name and must be simple. It is the place where data and information are stored.


Database Objects are the essential tools of relational database. These database objects helps to store,  view, edit and manipulate the data and information stored in database.

It can be used to hold and manipulate the data. Some of the examples of database objects are view,  sequence, indexes, form, query report etc.

Table: Basic unit of storage; composed rows and columns

View: Logically represents subsets of data from one or more tables

Sequence: Generates primary key values

Index: Improves the performance of some queries

Synonym: Alternative name for an object


Some Basic Terms used in Database

Schema: A schema is the structure of database which defines name of tables, data fields with data  types, relationships and constraints.

Instance: It defines data values in a record.

Entity: An entity is a thing or object in the real world that is different from other objects.

Attribute: Attribute is properties possessed by an entity or relationship.

Index: It is used to create indexes in database. It helps searching and sorting operation faster and  improves the performances of queries.

Query: It is the object of DBMS which is mainly used to extract and upgrade the necessary records  that are present in the database.

Form: It is object of database which is mainly used for data entry. It is easy to add, modify and  delete the records in form.

Report: Report are the printed output that is created from table or query. We can’t add, modify  and delete the records in report.


Keys of DBMS:

Key is a field that uniquely identifies the records, tables or data. Key in a table allows us to establish the  relation between multiple tables. Keys are also useful for finding the unique records or combination of  records from a large database tables.

Primary Key: A primary key is one or more columns in a table used to uniquely identify each row  in the table. Primary key cannot contain Null value.

A primary key is a special relational database table column (or combination of columns)  designated to uniquely identify each table record. A table cannot have more than one primary  key.

A primary key’s main features are: 

⮚ It must contain a unique value under the field.

⮚ It cannot contain null values.

⮚ Every row must have a primary key value.

Foreign Key: Foreign keys represent relationships between tables. A foreign key is a column whose  values are derived from the primary key of some other table.

Candidate Key: If a relational schema has more than one key, that is called a candidate key. All  the keys which satisfy the condition of primary key can be candidate key. There can be any number  of candidate keys that can be used in place of the primary key if required.

Alternate Key/ Secondary Key: Alternative keys are those candidate keys which are not the  primary key. There can be only one primary key for a table. Therefore all the remaining candidate  keys are known as alternative.

Compound Key: It has two or more attributes that allow you to uniquely recognize specific record.  It is possible that each column may not be unique by itself within the database.

SQL (Structured Query Language):

It is an international standard database query language for accessing and managing data in the database.

Features of SQL

  1. DDL (Data Definition Language): DDL is used by the database designers and programmers to specify the content and structure of the table. It is used to define the physical characteristics of records. It includes commands that manipulate the structure of objects such as views, tables, and  indexes, etc.
» CREATE: Create is used to create the database or its objects (like table, index, function, views, store  procedure and triggers).
» DROP: Drop is used to delete objects from the database.
» ALTER: Alter is used to alter the structure of the database.
» TRUNCATE: Truncate is used to remove all records from a table, including all spaces allocated for the  records are removed
» COMMENT: Comment is used to add comments to the data dictionary.
» RENAME: Rename is used to rename an object existing in the database.


  1. DML (Data Manipulation Language): DML is related with manipulation of records such as retrieval, sorting, display and deletion of records of data. It helps user to use query and display reports of the table. So it provides technique for processing the database.
» SELECT: It is used to retrieve data from a database.
» INSERT: It is used to insert data into a table.
» UPDATE: it is used to update an existing data in table.
» DELETE: It is used to delete record from table.


  1. DCL (Data Control Language): DCL provides additional features for security of table or database. It includes commands for controlling data and access to the database. Examples of these commands are commit, Rollback, Grant etc. .
GRAND: It gives user’s access privileges to database.
 ⮚ REVOKE: It is used withdraw users’ access privileges given by using the GRANT command.


Database Model:

A Database model defines the logical design and structure of a database and are used to show how data  will be stored, accessed and updated in a Database Management System. It refers to the layout of a  database and helps in designing a database.

  1. Hierarchical database model: this is one of the oldest types of database models. In this model data is represented in the form of records. Each record has multiple fields. All records are arranged in database as tree like structure. The relationship between the records is called parent child  relationship in which any child record relates to only a single parent type record.



2. Network database model: It replaced hierarchical network database model due to some limitations on the model. Suppose, if an employee relates to two departments, then the hierarchical database model cannot arrange records in proper place. So a network database model was created to arrange a  non-hierarchical database. The structure of the database is more like a graph rather than a tree structure. A network database model is a database model that allows multiple records to be linked to the same owner file. The network model allows each child to have multiple parents.



  1. Relational database model: in this model, the data is organized into tables which contain multiple rows and columns. These tables are called relations. A row in a table represents a relationship among a set of values. Since a table is a collection of such relationships, it is generally referred to  the mathematical term relation, from which the relational database model derives its name.

We notice from below table, here each student has a unique roll number and has marks of subject.  Here Roll makes relation between these two tables.



  1. Object oriented database model: In the object-oriented model, both data and their relationships are contained in a single structure known as an object. An Object-Oriented Model reflects a very different way to define and use entities. An object includes information about relationships  between the facts within the object, as well as information about its relationships with other  objects. An objects include data, various types of relationships, and operational procedures, the  object becomes self-contained, thus making the object-at least potentially-a basic building block  for autonomous structures.




Entity Relationship Diagram:

The diagrammatic representation of entities attributes and relationship is called E-R diagram. The  E-R diagram is an overall logical structure of a database that can be expressed graphically. It was  developed to facilitate database design. It is graphical representation of database.

Components of E-R Diagram

Entity: An entity is defined as anything about which data to be collected and stored.

Relationships: Relationships describes associations among data. Most relationships  describes associations between two entities.

Attribute: Attribute describes particular characteristics of the entity.

Relationship and its types:

A relationship is an association among several entities and represents meaningful dependencies between  them. It is represented by diamond. There are 3 types of relationship:

  1. One to one
  2. One to many
  3. Many to many

  1. One to one: if one record of an entity is related with only one record of another entity then such type of relationship is called one to one relationship.

  1. One to many: If one instance of one entity is related with many instances of other entity then it is called the one to many relationship.

  1. Many to many: If many instances of the one entity are related with many instances of another entity then it is called many to many relationship.


Concept of Normalization

Normalization is a database design process in which complex database table is broken down into simple  separate tables. It makes data model more flexible and easier to maintain.

⮚ Database Normalization is a technique of organizing the data in the database. It is a systematic  approach of decomposing the tables to eliminate data redundancy and inconsistency. The data is  said to be redundant if there is duplicate or repeated data in the table.

⮚ Normalization divides the larger table into the smaller table and links them using relationship. It  increase clarity in organizing data in the database.

For example:  

Below table shown is our database without normalized. Here in table we can see that for the large records  of this table, there would be multiple data row of same values especially in the country and city column.  So, we can normalize the table by splitting it into two tables where one table only stores the location area  of each person name and could be referenced by some unique id. Say Area code.

Id Name Country City
101 Alex Nepal Kathmandu
102 Martin India Delhi
103 Melman Nepal Kathmandu
104 Gloria Japan Tokyo

The above table can be normalized in two tables as below:

Country City Area Code
Nepal Kathmandu N1
India Delhi I1
Japan Tokyo J1


Id Area Code Name
101 N1 Alex
102 I1 Martin
103 N1 Melman
104 J1 Gloria


Advantages of Normalization:

Disadvantages of Normalization:


Types of Normalization
  1. 1NF (First Normal Form):

A table is said to be in first normal form if it has atomic values. There shouldn’t be any repeating  groups of attribute in the table. First normal form sets the very basic rules for an organized  database.

  1. 2NF (Second Normal Form):

A table is said to be in 2NF if it is a First normal form and it doesn’t have the partial dependency. Second normal form further addresses the concept of removing duplicate data. o It should be in the first normal form.

  1. 3NF (Third Normal Form):

Third normal form goes one large step further.


In Details Normalization with Examples


A table is said to be un-normalized when there is repetition of data in a table. In un-normalized table  records are not atomic. Let’s take an example of unnormalized table.

Un-normalized table:                 

Table No.1

Roll No. Name Faculty Subject
1 Sundar ICT Java, OS
2 Mukesh ICT Network
3 Ganesh ICT C, Web
  1. 1NF (First Normal Form):

A table is said to be in first normal form if it has atomic values. There shouldn’t be any repeating groups  of attribute in the table. Following are the main rules for table to be in 1NF:

⮚ Table should have single (atomic) valued attributes/columns.

⮚ Values stored in columns should be of same domain.

⮚ Columns name should not be repeated in table.

⮚ The order of column names doesn’t matter.

The table given above in un-normalized data meets the three requirements among four to be in first  normal form. In the subject column more than one subject are stored in a single column for two students.  But, each column must contain atomic value to be in first normal form. And the problem is solved in the  table given below:

Example of 1NF for above table No.1 

Table No.2

Roll No. Name Faculty Subject
      1 Sundar ICT Java
      1 Sundar ICT OS
     2 Mukesh ICT Network
     3 Ganesh ICT Web
     3 Ganesh ICT C

Though, some values are repeated but all columns are atomic for each record /row.

  1. 2NF (Second Normal Form):

A table is said to be in 2NF if it is in First normal form and it doesn’t have the partial dependency. i.e.  each attributes should functionally depend on primary key. Rules for 2 NF:

⮚ A table should be in first normal form.

⮚ There must not be partial dependency.

⮚ Partial dependency exists when any attribute of a table depends on only one part of a  composite primary key (primary key combining more than one field) and not on the  complete primary key.

⮚ To remove partial dependency, a table can be divided and attributes creating partial  dependency are removed in some other tables.


Situation of Dependency: 

Let’s take an example of table student with student_id, name, address and age as its columns.

Student_id Name Address age

Here student_id is the primary key which can identify each records uniquely and can be used to fetch  any row of data from this table.

Student_id Name Address Age
15 Ganesh KTM 17
16 Janaki BKT 17

Here we can get name, address and age of the student easily from their student_id. Which means each  column can be fetched using primary key. So, all needed is student_id and every other column depends  on it or can be fetched using it.

This is called dependency or functional dependency. And this kind of dependency must be in table to be  in second normal form.


Situation for partial dependency: 

In above table a single filed student_id uniquely identifies the all the records of the table. But in some  cases combination of two or more columns or fields makes the primary key. Where more than one field  acts as primary key. Lets create a table named subject with fields subject_id and subjectname.

Subject_id Subjectname
101 Math
102 Science
103 Nepali

Above we have two tables: student and subject for storing student’s and subject’s information. Now, let’s  make a table named Mark storing student’s mark in respective subjects with subject teacher.

Score_id  Student_id Subject_id Marks Teacher
1 15 101 55 Bishnu
2 15 102 65 Umesh
3 16 103 88 Janvi

Note: the above table is not in 2nd normal form.

In above table student_id is used to get student’s information where as subject_id is used to get subject  name. The combination of student_id and subject_id is the primary in above table. It is because if we  want to get mark of student with id 15 then we cannot get because we don’t know which subject. Here  we have to give sudent_id and subject_id to uniquely identify any row.

Is there a partial dependency in above table? Obviously, yes. In the given table Mark column name  teacher is only dependent on the subject, for math there is Bishnu for science Umesh and so on. But the  primary key is the combination of student_id and subject_id, teacher’s name depend only on subject, i.e.  subject_id not on the student id.

This situation is known as partial dependency, where an attribute/ column in table depends on only a  part of primary key not on the whole key.


Removing the partial dependency: 

Above table can be normalized in second normal form by removing teacher’s name from the Mark table  adding it to Subject table. 


Subject_id Subjectname Teacher
101 Math Bishnu
102 Science Umesh
103 Nepali Janvi



Score_id Student_id Subject_id Marks
1 15 101 55
2 15 102 65
3 16 103 88



⮚ For table to be in second normal form, it should be in first normal form.

⮚ Partial dependency exists, when non primary key attribute depends only on a part of  primary key instead of complete primary key.

⮚ Partial dependency can be removed by breaking a table and removing attributes causing  partial dependency.

    1. 3NF (Third Normal Form):

    A table is said to be in third normal form, if it is second normal form and it doesn’t have any  transitive dependency in primary key. The elements that are not dependent on primary key are removed.  Transitive dependency occurs in table when a non-primary key attribute depends upon another non  primary key attribute. All non-primary key attribute must dependent on primary key attribute or  attributes.

    Transitive Dependency? 

    Transitive Dependency occurs when a non-primary key attribute depends upon another non primary key  attribute instead of primary key attribute or primary key.

For instance: 

In the above table Mark, let’s add some more information such as Exam_name and Full_mark.

Score_id Student_id Subject_id Marks Exam_name Full_marks
1 15 101 55 First Term 500
2 15 102 65 First Term 500
3 16 103 88 Second Term 300

In above table, student_id and subject_id are the primary key. The column exam_name depends on both  student_id and subject_id. But, the Full_marks depends on the Exam_name. The first term exam might  have 500 full mark but the second term may have 300 or others. Here exam_name is neither primary key  nor the part of primary key still, Full_mark depends on it. So, here full_mark which is non-primary key  attribute depends on another nonprimary key attribute known as Exam_name. This situation is known as  transitive dependency.


Removing Transitive Dependency: 

Again, table should be broken into small individual tables to remove it. So we need to remove those  fields which are creating transitive dependency. Which looks like.

Score Table 

Score_id Student_id Subject_id Marks Exam_Id
1 15 101 55 11
2 15 102 65 12
3 16 103 88 13


Exam Table

Exam_id Exam_Name Full_Marks
11 First Term 500
12 Second term 300

Benefits of removing transitive dependency: 

⮚ Amount of data duplication is reduced.

⮚ Data integrity is achieved.

Note: Normalization does not eliminate data redundancy. Instead, it reduces the redundancy.


Example of normalization:

 Un-normalized Table:

Employee Id Name Address Department
101 Ram Kathmandu Sales
102 Bikky Bhaktapur Marketing, Export
103 Anusha Lalitpur import


First Normal Form:

Employee Id Name Address Department
101 Ram Kathmandu Sales
102 Bikky Bhaktapur Marketing
102 Bikky Bhaktapur Export
103 Anusha Lalitpur import


Second Normal Form:

Let’s take a table employee having more than one department.

Employee Id Department Salary
101 Sales 20000
102 Marketing 25000
102 Export 25000
103 Import 20000

Here the non-primary key attribute salary dependent on the employee id only. Here Employee id and  department are the candidate key. This violates the rule that “no non primary attribute is dependent on  the part of primary key or on the subset of candidate key.”

To make table in 2NF we can break it as:

Employee Id     Salary
101 20000
102 25000
102 25000
103 20000


Employee Id     Department
101 Sales
102 Marketing
102 Export
103 Import


Third Normal Form:

Employee Id Name   Department HoD
101 Rikesh HR Mukesh
102 Binita Marketing Mukesh
102 Jagdish Store Bikash

Here, Employee Id is the primary key and all other are non-primary key attributes. The non- primary key  attribute HoD is dependent on non-primary key attribute Department. Here, transitive dependency  occurs. To remove it we can decompose table as:

Employee Id Department Id Name
101 A10 Rikesh
102 A11 Binita
102 A12 Jagdish


Department Id Department Name
A10 HR Mukesh
A11 Marketing Mukesh
A12 Store Bikash


Another Normalization

Example 1 

Unnormalized database

Emp_code January
Emp_name February
Address March
Contact no. April
Date of Birth May
Department June
Designation July
Basic_salary Daily_allowance
Travel_Allownace Gross_salary
Tax Provident_fund


Normalized database

Employee Salary Month
Emp_code Basic salary January
Emp_name Travel allowance February
Address Daily allowance March
Contact no. Gross salary April
Date of birth Provident Fund May
Department Tax June
Designation July

Example 2

Name Roll Class Sub_name Sub_marks Sub_name Sub_marks
Ram 1 11 Computer 95 Account 78
Sita 1 12 Computer 98 Account 80
Hari 2 11 Computer 80 Account 82
Shyam 2 12 Computer 92 Account 83

In above table, we can see that column of subject nome and marks are repeated which are eliminated in  1NF.

Name Roll Class Sub_name Sub_marks
Ram 1 11 Computer 95
Ram 1 11 Account 78
Sita 1 12 Computer 98
Sita 1 12 Account 80
Hari 2 11 Computer 80
Hari 2 11 Account 82
Shyam 2 12 Computer 92
Shaym 2 13 Account 83

In above table name depends upon roll no and class, subject name only depends upon class, subject marks  depends upon name and subject_name. Hence, above table can be decomposed as 2NF:

It removes the column that are not dependent on primary key using 3NF above table can be decomposed as:


Centralized database system Vs. Distributed database system:

Centralized database system:

⮚ The database system where data and information are stored in the centralized server or  centralized database system.

⮚ The data stored in database are accessed from different locations through several applications.  The information (data) is stored at a centralized location and the users from different locations  can access this data.

⮚ This type of database contains application procedures that help the users to access the data even  from a remote location.


⮚ It decreases risk of data manipulation. i.e. manipulation of data will not affect the core data.

⮚ Data consistency is maintained as it manages data in a central repository.

⮚ It provides better data quality, which enables organizations to establish data standards.

⮚ It is less costly as fewer vendors are required to handle the data sets.


⮚ The size of centralized database is large which increases the response time of fetching data.

⮚ It is difficult to update the centralized database.

⮚ If server gets damaged entire data will be lost.

Distributed database system:

⮚ Distributed database doesn’t store all data and information in the single but store on various sites  or places, which are connected by the help of communication, links which helps them to access  the distributed data easily.

⮚ In distributed database various portions of a database are stored in multiple different locations  along with the application procedures which are replicated and distributed among various points  in a network.


⮚ The system can be expanded by including new computers and connecting them to the  distributed system.

⮚ Distributed database is more reliable than centralized database.

⮚ The performance and service are better.

⮚ Large numbers of users are supported.

⮚ One server failure will not affect the entire data set.


⮚ It is difficult to administrate and manage the database

⮚ It is expensive to set up.

⮚ This database has high risk of hacking and data theft.


Difference between centralized and distributed system

Centralized database Distributed database system
1. Simple type. 1. Complex type.
2. Located on particular location. 2. Located in many geographical locations.
3. Consists of only one server. 3. Contains servers in several locations.
4. Suitable for small organizations. 4. Suitable for large organizations.
5. Less chance of data lost. 5. More chances of data hacking, lost.
6. Maintenance is easy and security is high. 6. Maintenance is not easy and security is low.
7. Failure of system makes whole system down. 7. Failure of one server does not make the whole system down.
8. There is no feature of load balancing. 8. There is feature of load balancing.
9. Data traffic rate is high. 9. Data traffic rate is low.
10. Cost of centralized database system is low. 10. Cost of distributed database system is high.


Data dictionary:

A data dictionary is a file which contains meta-data that is data about data. It also called information  system catalogue. It keeps all the data information about the database system such as location, size of  the database, tables, records, fields, user information, recovery system, etc.


Data integrity:

Data integrity referees to the validity or consistency of data in database. It ensures that the data should  be accurate and consistent.

Mainly there are 3 types of data integrity constraints used in the database system. They are as:

  1. Domain integrity constraints: It defines a set range of data values for given specific data field. And  also    determines whether null values are allowed or not in the data field.
  2. Entity integrity constraints: It specify that all rows in a table have a unique identifier, known as the primary key value and it never be null i.e. blank.
  3. Referential integrity constraints: It exists in a relationship between the two tables in a database. It ensures that the relationship between the primary keys in the master table and foreign key in child table are always maintained.


Data Security:

Data security is protection of data in database system against unauthorized access, modification, failure,  losses or destruction. The authorized access means only right people can get the right access to the  right data.


DBA (Database Administrator)

DBA is the most responsible person in an organization with sound knowledge of DBMS. He/she is the  overall administrator of the program. He/she has the maximum amount of privileges for accessing  database and defining the role of the employee which use the system. The main goal of DBA is to keep  the database server up to date, secure and provide information to the user on demand.

Qualities of good DBA:

  1. He/she should have sound and complete knowledge about DBMS and its operation.
  2. He/she should be familiar with several DBMS packages such as MS Access, MYSQL, Oracle etc
  3. He/she should have depth knowledge about the OS in which database server is running.
  4. He/she should have good understanding of network architecture.
  5. He/she should have good database designing skill.


  1. DBA has responsibility to install, monitor, and upgrade database server.
  2. He/she should has responsibility to maintain database security by creating backup for recovery.
  3. He/she has responsibility to conduct training on the uses of database.
  4. DBA defines user privilege, relationships and manages form, reports in database.


The SQL statement for creating, dropping, and altering database and table

XAMPP provides a GUI environment to perform any operations on the database. However, it also  provides an option to use SQL statements to perform any operations SQL statements are used in the  SQL menu in phpMyAdmin. The SQL statements used in XAMPP also work well with most of the  databases.


Creating a database:

Syntax: CREATE DATABASE databasename;

Example: CREATE DATABASE School;


Dropping the database (deleting the database):

Syntax: DROP DATABASE databasename:

Example: DROP DATABASE School:


Creating a table:

Syntax: CREATE TABLE table_name (column1 datatype, column2 datatype, column3 datatype….)

Example: CREATE TABLE Students (StudentID int, FName varchar(255), LName varchar(255), Address varchar(255), Class varchar(255));


Altering table adding, deleting, or modifying columns in an existing table

Adding column Syntax:

Syntax: ALTER TABLE table name ADD column_name datatype

Example: ALTER TABLE Students ADD Email varchar(255));


Deleting column

Syntax: ALTER TABLE table name  DROP COLUMN column_name;

Example: ALTER TABLE Students DROP COLUMN Email;


Modifying column (changing the data type of a column in a table)

Syntax: ALTER TABLE table name MODIFY COLUMN column_name datatype;

Example: ALTER TABLE Students MODIFY COLUMN Class int;


Deleting table

Syntax: DROP TABLE table_name;

Example: DROP TABLE Students;


Inserting data

Syntax: INSERT INTO table name (column1, column2 column3,…)  VALUES (valuel, value2, value3);

Example: INSERT INTO Students (StudentID,  FName, LName, Address, Class) VALUES (‘101’, ‘Ram’, Sharma’, Pokhara’, 7);


Selecting data in selecting data from a database);

Syntax: SELECT column1, FROM table name column2.


SELECT * FROM Students; (This will select all the columns from the table Students]

SELECT  FNAME, LNAME FROM Students: [This will select only the First Name and Last Name from the table Students.]


Selecting data using conditions

Syntax:  SELECT column1, column2….  FROM table_name WHERE condition;

Example: SELECT Roll_No, FName FROM Students WHERE Roll_No>10 AND Roll_No<100;


Selecting unique data

Syntax: SELECT DISTINCT column_name FROM table_name;

Example: SELECT DISTINCT address FROM Students;


Sort data

Syntax: SELECT column1, column2, … FROM table_name ORDER BY column1 [ASC|DESC];

Example: SELECT Fname, Lname FROM Students ORDER BY Score;


Deleting data

Syntax: DELETE FROM table_name WHERE condition;

Example: DELETE FROM customers WHERE customer_id = 123;


Updating data using conditions

Syntax: UPDATE table_name SET column1 = value1, column2 = value2, … WHERE condition;

Example: UPDATE Students SET LName = “Sharma” WHERE Roll_No = 121;