Viva Question Answers ( DBMS, JavaScript, C Programming, PHP)

DBMS Viva Question

What is the difference between Data and Information?

  • Data: Raw facts or symbols without context. “100”, “Ram Shrestha”, “Red”, “12.5°C” are all examples of raw facts or symbols.
  • Information: Processed data with context and meaning. “There are 100 units of Red product in stock.”, “The temperature is 12.5 degrees Celsius.” are examples of data that have been processed and organized into meaningful contexts, providing useful insights or understanding.

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

  • Field: A single piece of data within a record or row.
  • Attribute: A characteristic or property of an entity. (Column)
  • Record: A collection of data in a single row. (Row, Tuple)
  • Table: A collection of related data organized into rows and columns.
  • Database: A structured collection of data organized and managed for efficient retrieval and manipulation.

What is a Database Management System?

  • A software system that allows users to define, create, maintain, and control access to databases. Ex: MySQL, PostgreSQL, Oracle, SQLServer, MS Access, etc.

What are the types of keys in DBMS?

  • Primary Key: Unique identifier for a record in a table.
  • Foreign Key: Establishes a relationship with the primary key of another table.
  • Candidate Key: Minimal set of attributes that uniquely identify a record.
  • Alternate Key: Candidate key not selected as the primary key.

What are the advantages of DBMS over Excel?

  • Data Integrity: Enforces data accuracy and consistency.
  • Data Security: Provides robust access control and encryption.
  • Concurrent Access: Allows multiple users to manipulate data concurrently.
  • Scalability: Efficiently handles large volumes of data.
  • Data Analysis: Supports advanced querying and reporting capabilities.

Differentiate between DDL and DML.

  • DDL (Data Definition Language): Defines database structure (CREATE, ALTER, DROP).
  • DML (Data Manipulation Language): Manipulates data (INSERT, UPDATE, DELETE, SELECT).

What is SQL?

  • SQL stands for Structured Query Language. It is a standard language used for managing and manipulating relational databases.

What is the purpose of SQL?

  • The purpose of SQL is to manage and manipulate data in relational databases.

What is the purpose of the SELECT statement in SQL?

  • The SELECT statement is used to retrieve data from one or more tables in a database.

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

  • * means all. So it will select all columns.

What is the difference between DELETE and Drop commands?

  • DELETE command is used to remove specific rows from a table, while DROP command is used to remove entire database objects, such as tables, views, indexes, or constraints, from the database.

What is the difference between DELETE and TRUNCATE commands?

  • DELETE command is used to remove specific rows from a table, while TRUNCATE command is used to remove all rows from a table.

What is the purpose of the WHERE clause in SQL?

  • The WHERE clause is used to filter records based on a specified condition.

What is the purpose of the INSERT statement in SQL?

  • The INSERT statement is used to add new rows of data into a table.

What is the purpose of the UPDATE statement in SQL?

  •  The UPDATE statement is used to modify existing data in a table.

What is the purpose of the DELETE statement in SQL?

  • The DELETE statement is used to remove existing rows of data from a table.

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

  •  The ORDER BY clause is used to sort the result set of a query based on specified columns.

JavaScript Viva Question

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

  • Client-side scripting manipulates web page content on the client’s browser, while server-side scripting generates content on the server.

Name some popular client-side scripting languages.

  • JavaScript, HTML, and CSS.

How do we create comments in JavaScript?

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

  • Single-line comments: These comments begin with // and continue until the end of the line. They are used for brief explanations or annotations.
    // This is a single-line comment
  • Multi-line comments: These comments begin with /* and end with */. They can span multiple lines and are typically used for longer explanations or commenting out blocks of code.
    This is a multi-line comment.
    It can span multiple lines and is useful for longer explanations.

Explain about Global and Local Variable.

     Global Variables:

  • Declared outside of any function.
  • Accessible from anywhere in the program.
  • Exist throughout the entire program execution.
  • Example:
    var globalVar = 10;
    function myFunction()

     Local Variables:

  • Declared within a function.
  • Accessible only within the function where they are declared.
  • Exists only during the execution of the function.
  • Example:
    function myFunction() 
               var localVar = 20;

Differentiate between null and undefined.


  • It represents the intentional absence of any object value.
  • null is a primitive data type.
  • It is explicitly assigned to a variable to indicate the absence of a value.
  • Example:
    var x = null;


  • It represents the absence of a value, typically when a variable has been declared but not assigned a value.
  • undefined is a primitive data type.
  • It is automatically assigned to variables that have not been initialized or do not have a value assigned.
  • Example:
    var y;

How do you create an array in JavaScript?

  • var myArray = [10, 20, 30, 40, 50];
  • console.log(myArray[0]); // Output: 10
  • console.log(myArray[2]); // Output: 30

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

  • Responds to user actions or browser events, like clicks or page loads.

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

  • JavaScript is a scripting language used for creating interactive and dynamic web content, enhancing user experience through client-side scripting.

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

  • Methods include inline scripting, external script files, and script tags within the HTML document.

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

  • Attributes include src (for external scripts), type (specifying the script type), and async or defer (for controlling script execution).

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

  • Placing scripts in the <head> delays rendering, while placing them at the end of the <body> improves page loading.

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

  • Inline JavaScript is embedded directly within HTML tags. Advantages include simplicity, but it can clutter HTML and reduce code maintainability.

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

  • JavaScript can access and modify HTML elements using methods like getElementById, querySelector, and properties like innerHTML and style.

Explain the difference between JavaScript and Java.

  • JavaScript is a scripting language primarily used for client-side web development, while Java is a general-purpose programming language often used for server-side applications.

What are the basic building blocks of JavaScript programs?

  • The basic building blocks include variables, data types, operators, control structures (like if statements and loops), functions, and objects.

What are data types in JavaScript?

  • Data types in JavaScript include number, string, boolean, null, undefined, and symbol (introduced in ES6).

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

  • Type coercion is the automatic conversion of one data type to another. For example, 5 + '5' results in the string '55' due to implicit type coercion.

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

  • A variable is a named storage location for holding data. You declare a variable using the var, let, or const keyword, followed by the variable name.

Explain the rules for naming variables in JavaScript.

  • Variable names must begin with a letter, dollar sign $, or underscore _, followed by letters, digits, dollar signs, or underscores. They cannot be reserved words.

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

  • var declares a variable with function scope, let declares a variable with block scope, and const declares a constant variable that cannot be reassigned.

Explain the concept of hoisting in JavaScript variable declaration.

  • Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their containing scope during compilation, allowing them to be used before they are declared.

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

  • Operators in JavaScript perform operations on operands. They fall into categories such as arithmetic, assignment, comparison, logical, bitwise, and ternary.

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

  • Unary operators operate on a single operand (e.g., ++x), binary operators operate on two operands (e.g., x + y), and ternary operators operate on three operands (e.g., condition ? value1 : value2).

Explain the use of arithmetic operators in JavaScript with examples.

  • Arithmetic operators perform mathematical calculations. Examples include addition +, subtraction -, multiplication *, division /, and remainder %.

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

  • Operator precedence determines the order in which operators are evaluated, while associativity determines the order of evaluation for operators with the same precedence.

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

  • Comparison operators compare two values and return a Boolean result (true or false). Logical operators perform logical operations and return a Boolean result.

What are the various pop-ups in JavaScript?

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

  • Alert:
    • Displays a message in a dialog box with an OK button.
    • Syntax:


  • Prompt:
    • Displays a dialog box with a message, an input field for the user to enter data, and OK and Cancel buttons.
    • Syntax:
                                var result = prompt("Enter your name:", "");
  • Confirm:
    • Displays a dialog box with a message and OK and Cancel buttons.
    • Syntax:
                                var result = confirm("Are you sure?");

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

  • console.log():
    • Used for debugging and logging information to the browser’s console.
    • Logs messages, variables, objects, or other data to the console.
    • Messages logged with console.log() are visible only to developers in the browser’s console and are not displayed on the webpage itself.
    • Example:
                                    console.log("Hello, world!");
  • document.write():
    • Used to write HTML content directly to the document.
    • Writes the specified content directly to the webpage, altering the document’s HTML structure.
    •  Content written with document.write() is added directly to the document and is visible to users on the webpage.
    • Example:                    

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.

  • var result = parseInt(“123”); // Returns 123
  • var result = Number(“123”); // Returns 123

What is a function in JavaScript?

  • A function is a block of reusable code that performs a specific task when called or invoked.

How do you declare a function in JavaScript?

  • You can declare a function using the function keyword followed by the function name, parameters (if any), and function body enclosed in curly braces.

Explain the difference between function declarations and function expressions.

  • Function declarations are defined using the function keyword followed by a name, while function expressions are created by assigning a function to a variable.

What are the parameters and arguments in a function?

  • Parameters are variables listed in the function definition, while arguments are the actual values passed to the function when it is called.

Explain the concept of return values in functions.

  • Return values are values returned by a function after it has been executed. They can be any data type and are specified using the return keyword.

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

  • The if-else statement is a conditional statement used to execute code blocks based on whether a condition is true or false.

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

  • The if-else-if statement allows you to test multiple conditions sequentially and execute corresponding code blocks.

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

  • The switch-case statement evaluates an expression and executes code blocks based on matching cases.

What are the types of loops in JavaScript?

  • for loop
  • while loop
  • do…while loop
  • for…in loop
  • for…of loop

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

  • The for loop is used to repeatedly execute a block of code a specified number of times. It consists of initialization, condition, and iteration expressions.

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

  • The while loop executes a block of code as long as a specified condition evaluates to true.

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.

  • Objects in JavaScript are collections of key-value pairs, where each value can be a primitive data type, another object, or a function.

How do you create objects in JavaScript?

  • Objects can be created using object literals {}, constructor functions with the new keyword, or Object.create() method.

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

  • Events in JavaScript are actions or occurrences that happen in the system or in the DOM, triggered by user interaction or browser actions.

How do you handle events in JavaScript?

  • Events are handled by attaching event listeners to DOM elements using methods like addEventListener().

What is the Image object in JavaScript?

  • The Image object represents an HTML <img> element, allowing manipulation of images dynamically within JavaScript.

How do you create an Image object in JavaScript?

  • You create an Image object using the new Image() constructor or by assigning a new image element to a variable.

What properties and methods does the Image object provide?

  • Properties include src, width, height, alt, and methods include addEventListener(), removeEventListener(), complete, onload, and onerror.

What is the Form object in JavaScript?

  • The Form object represents an HTML <form> element, providing access to its properties and methods for form manipulation.

How do you access a Form object in JavaScript?

  • You access a Form object using the document.forms collection or by using the getElementById() or querySelector() methods.

What properties and methods does the Form object provide?

  • Properties include action, method, elements, and methods include submit(), reset(), and addEventListener().

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

  • Form validation ensures that user input meets specified criteria before submission, maintaining data integrity and enhancing user experience.

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

  • Client-side validation occurs in the browser before form submission, while server-side validation occurs on the server after submission.

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

  • Common techniques include using JavaScript functions, regular expressions, and HTML5 form validation attributes like required, minlength, etc.

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

  • jQuery is a JavaScript library that simplifies DOM manipulation, event handling, and AJAX interactions by providing concise and cross-browser-compatible methods.

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

  • Include jQuery by adding a <script> tag referencing the jQuery library. Syntax for selecting elements: $(selector).

C Programming Viva Question

What is a function in C programming?

  • A function is a block of code that performs a specific task. It has a name, a return type, parameters (optional), and a body.

What is the purpose of using functions in C?

  • Functions allow code reusability, modular programming, and easier maintenance by breaking down a program into smaller, manageable parts.

How do you define a function in C?

  • Function definition includes specifying the return type, function name, parameters (if any), and the function body enclosed in curly braces.

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

  • A function declaration provides the function signature (return type, name, parameters) without the function body. A function definition includes both the function signature and the body.

What is a function prototype in C?

  • A function prototype is a declaration of the function that provides its signature (return type, name, parameters) without the function body. It informs the compiler about the function’s existence.

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

  • A library function is provided by the programming language or external libraries, while a user-defined function is created by the programmer.

What are the advantages of using functions in programming?

  • Functions promote code reusability, improve code readability, facilitate modular programming, and simplify debugging and maintenance.

What are function parameters?

  • Function parameters are variables declared in the function header that receive values passed from the calling code.

How are function parameters passed in C?

  • Function parameters in C are typically passed by value, meaning a copy of the parameter’s value is passed to the function. However, C also supports passing parameters by reference using pointers.

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

  • In call by value, a copy of the parameter’s value is passed to the function, while in call by reference, the address of the parameter is passed, allowing the function to directly modify the original value.

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

  • The return type is specified before the function name in the function declaration and definition.

Can a function return multiple values in C?

  • No, C functions can only return one value. However, you can use pointers or structures to simulate returning multiple values.

What is recursion in C?

  • Recursion is the process in which a function calls itself directly or indirectly.

What are the necessary conditions for recursion?

  • A base case to terminate the recursion and a set of rules to reduce all other cases towards the base case.

How does recursion work in C?

  • Recursion works by breaking down a complex problem into smaller, similar subproblems and solving them recursively until reaching the base case.

What is a structure in C programming?

  • A structure is a user-defined data type that allows combining different types of variables under a single name.

How do you define a structure in C?

  •  A structure is defined using the struct keyword followed by the structure name and a list of member variables enclosed in curly braces.

What is the difference between structure definition and declaration?

  • Structure definition specifies the structure’s layout and member variables, while structure declaration creates variables of the defined structure type.

How do you initialize a structure in C?

  • A structure can be initialized by providing values for its member variables within curly braces at the time of declaration.

How is the size of a structure calculated in C?

  • The size of a structure is determined by summing the sizes of its member variables, with padding added for alignment purposes.

How do you access members of a structure in C?

  • Members of a structure are accessed using the dot (.) operator followed by the member name.

What is an array of structures in C?

  • An array of structures is a collection of multiple structures of the same type stored consecutively in memory.

What is a union in C programming?

  • A union is a user-defined data type that allows storing different types of data in the same memory location.

How do you define a union in C?

  • A union is defined using the union keyword followed by the union name and a list of member variables enclosed in curly braces.

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

  • In a structure, all member variables have their own memory locations, while in a union, all member variables share the same memory location. Additionally, a structure allocates memory for the largest member, whereas a union allocates memory just enough to hold the largest member.

What is a pointer in C programming?

  • A pointer is a variable that stores the memory address of another variable or object.

What is a data file in C programming?

  • A data file is a file used to store data persistently on a storage device, such as a hard drive or flash drive, for later retrieval and manipulation by a program.

What is the purpose of using data files in programming?

  • Data files allow programs to store and retrieve data between different program runs, enabling data persistence and sharing across multiple instances of the program.

What is a sequential file?

  • A sequential file is a type of data file where records are stored in sequential order, and data is accessed sequentially from start to end.

What is a random file?

  • A random file is a type of data file where records are stored at specific locations within the file, allowing for direct access to individual records using their record numbers or keys.

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

  • The putw() function is used to write an integer to a binary file, while the getw() function is used to read an integer from a binary file.

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

  • The putc() function is used to write a character to a file, while the getc() function is used to read a character from a file.

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

  • fscanf() is used to read formatted data from a file, while fprintf() is used to write formatted data to a file.

How do you open a file in C for reading?

  • You can open a file for reading using the fopen() function with the “r” mode.

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

  • Writing to a file overwrites its existing contents, while appending to a file adds new data to the end of the file without overwriting existing data.

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

  • You can close a file using the fclose() function, passing the file pointer as an argument.

PHP Viva Questions

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

  • Server-side scripting generates web content on the server before sending it to the client. Client-side scripting executes on the client’s browser.

Name some popular server-side scripting languages.

  • PHP, Python (with Django or Flask), Ruby (with Ruby on Rails), Java (with Spring Boot), and Node.js.

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

  • It receives HTTP requests, processes them, interacts with databases or resources, and sends back dynamic content as an HTTP response.

Explain the typical workflow of a server-side script.

  • Receive request, process input, execute logic, interact with databases, generate content, and send response.

What are the advantages of server-side scripting?

  • Better security, easier database integration, improved performance, and SEO support.

What are the hardware and software requirements for running PHP?

  • PHP can run on various operating systems like Windows, Linux, macOS, etc. It requires a web server such as Apache or Nginx and a PHP interpreter installed.

Explain the concept of object-oriented programming in PHP.

  • Object-oriented programming (OOP) in PHP allows us to structure code into classes and objects. It facilitates concepts like encapsulation, inheritance, and polymorphism.

What is the basic syntax of PHP?

  • PHP code is embedded within HTML, typically enclosed in <?php ?> tags. Statements end with a semicolon. It’s loosely typed, so variables do not need to be declared.

What are the various data types supported by PHP?

  • PHP supports data types like integers, floats, strings, booleans, arrays, objects, and resources.

Discuss the different types of operators in PHP.

  • PHP supports arithmetic, logical, and comparison operators. Arithmetic operators perform mathematical operations, logical operators deal with boolean logic, and comparison operators compare values.

How do you manipulate variables in PHP?

  • Variables in PHP can be manipulated by assigning new values, concatenating strings, performing mathematical operations, or using built-in functions for manipulation.

Explain database connectivity in PHP.

  • Database connectivity in PHP involves establishing a connection between PHP scripts and a database server, typically using functions like mysqli_connect() or PDO.

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

  • The steps include establishing a connection to the database server, selecting the appropriate database, executing SQL queries, fetching results, and handling errors.

How do you make SQL queries in PHP?

  • SQL queries in PHP are made using functions like mysqli_query() or PDO::query(), passing the SQL statement as a parameter.

What does fetching data sets mean in PHP?

  • Fetching data sets in PHP refers to retrieving rows of data from a database after executing an SQL query.

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

  • You can create an SQL database using PHP by executing SQL commands like CREATE DATABASE using functions like mysqli_query() or PDO::exec().

Discuss the process of displaying queries in tables using PHP.

  • To display queries in tables, you fetch data from the database, iterate over the results, and output them in HTML table format using echo or print statements.

How do you define a class in PHP?

  • A class in PHP is defined using the class keyword followed by the class name and a pair of curly braces containing properties and methods.

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

  • The ‘new’ keyword is used to instantiate objects from a class in PHP. It allocates memory for the object and calls the class constructor.

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

  • The == operator checks for equality of values, while the === operator checks for equality of both values and data types.

How do you declare and initialize variables in PHP?

  • Variables in PHP are declared using a dollar sign ($) followed by the variable name, and they can be initialized with an initial value using the assignment operator (=).

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

  • SQL injection is a type of security vulnerability where malicious SQL statements are inserted into input fields. It can be prevented in PHP by using prepared statements with parameterized queries.

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

  • The mysqli and PDO extensions in PHP provide interfaces for interacting with databases. They offer functions and classes for executing SQL queries, fetching results, and managing connections securely.

How do you handle errors during database connectivity in PHP?

  • Errors during database connectivity can be handled using functions like mysqli_connect_error() or PDO::errorInfo(), which provide error messages and codes for debugging.

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

  • Inheritance allows a class (subclass) to inherit properties and methods from another class (superclass). It promotes code reusability and allows for the extension of functionality.

What are the different types of loops supported in PHP?

  • PHP supports various loops like for, while, do-while, and foreach loops for iterating over arrays, executing code repeatedly based on conditions, or looping through database query results.

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

  • Constructor methods are called automatically when an object is instantiated, while destructor methods are called when the object is destroyed. Constructors are typically used for initialization tasks, while destructors are used for cleanup tasks.

How do you execute conditional statements in PHP?

  • Conditional statements in PHP are executed using if, else, elseif, and switch statements, allowing the program to make decisions based on specified conditions.

Explain the concept of method overloading in PHP.

  • PHP does not support method overloading in the traditional sense where multiple methods with the same name but different signatures can exist within a class. However, you can achieve similar functionality using variable-length argument lists and default parameter values.

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

  • The php.ini file is a configuration file used to customize PHP settings such as error reporting level, maximum upload file size, and database connection parameters.

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

  • Data from a form submitted via POST method can be retrieved using the $_POST superglobal array in PHP, where the keys are the names of form fields.

Explain the process of handling file uploads in PHP.

  • File uploads in PHP are handled using the $_FILES superglobal array, which contains information about the uploaded file such as name, type, size, and temporary location. The file is then moved to a permanent location on the server.

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

  • PHP scripts can encounter syntax errors, runtime errors, and logical errors. Syntax errors occur due to incorrect PHP syntax, while runtime errors occur during script execution, and logical errors result in unexpected behavior.

How do you include external PHP files within a script?

  • External PHP files can be included using include, require, include_once, or require_once statements in PHP, allowing reusable code to be incorporated into multiple scripts.

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

  • The ‘use’ keyword in PHP namespaces allows for the importing of classes or namespaces into the current scope, enabling shorter and cleaner code by avoiding fully qualified names.

Discuss the concept of autoloading classes in PHP.

  • Autoloading classes in PHP allows for the automatic loading of class files when they are first accessed, eliminating the need to manually include or require each class file.

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

  • The GET method submits form data in the URL, visible to users and limited in length, suitable for non-sensitive data. The POST method sends form data in the request body, not visible in the URL, and suitable for sensitive data.

What is the purpose of the global keyword in PHP?

  • The global keyword in PHP is used to access global variables from within a function’s scope, allowing variables defined outside the function to be manipulated within the function.

How do you handle sessions in PHP?

  • Sessions in PHP are handled using the $_SESSION superglobal array, which allows data to be stored and retrieved across multiple pages during a user’s visit to a website.

Explain the concept of method chaining in PHP.

  • Method chaining in PHP involves calling multiple methods on the same object in a single statement by returning the object itself from each method call, enabling a fluent interface.

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

  • The header() function in PHP is used to send HTTP headers to the client, allowing for tasks such as redirection, setting cookies, and specifying content types.

Discuss the significance of sanitizing user input in PHP.

  • Sanitizing user input in PHP is essential for preventing security vulnerabilities such as SQL injection and cross-site scripting (XSS) attacks by removing or escaping potentially harmful characters.

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

  • The empty() function in PHP is used to determine whether a variable is empty, meaning it does not exist, has a value of null, an empty string, or zero.

Explain the concept of method visibility in PHP classes.

  • Method visibility in PHP classes determines the accessibility of methods from outside the class. PHP supports public, private, and protected visibility modifiers, controlling access levels for methods.

How do you define constants in PHP?

  • Constants in PHP are defined using the define() function or the const keyword, providing a name and a value that cannot be changed during script execution.

Discuss the role of namespaces in PHP.

  • Namespaces in PHP provide a way to organize code into logical groups, preventing naming conflicts between classes and functions with the same name but different namespaces.

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

  • The setcookie() function in PHP is used to set cookies in the client’s browser, allowing data to be stored and retrieved across multiple page requests.

Explain the difference between require and include statements in PHP.

  • The require statement includes a file and generates a fatal error if the file cannot be included, whereas the include statement includes a file and generates a warning if the file cannot be included.