Top PHP Interview Questions and Answers

Q: What are the main features of PHP?

Key features include being open-source and cross-platform, loosely typed language, supports object-oriented programming, built-in support for databases like MySQL, integration with HTML/CSS/JavaScript, and supports frameworks like Laravel.

Q: How do you prevent SQL Injection in PHP?

Use prepared statements with PDO or MySQLi. Example: $stmt = $pdo->prepare('SELECT * FROM users WHERE email = ?'); $stmt->execute([$email]);

Introduction

Preparing for a PHP job interview requires a strong understanding of both fundamental and advanced concepts. Whether you are applying for a junior PHP developer role or a senior backend developer position, these top PHP interview questions and answers will help you impress your interviewer and secure your dream job.

This guide covers basic PHP interview questions, advanced PHP questions, OOP in PHP, Laravel interview questions, and real-world PHP programming challenges. All questions are crafted using high-ranking Google keywords to align with what hiring managers are searching for in 2025.

Basic PHP Interview Questions

1. What is PHP?

Answer:

PHP stands for Hypertext Preprocessor. It is an open-source, server-side scripting language designed for web development. PHP code is executed on the server and can be embedded into HTML.

2. What are the main features of PHP?

Answer:

Open-source and cross-platform
Loosely typed language
Supports object-oriented programming
Built-in support for databases like MySQL, PostgreSQL
Integration with HTML, CSS, and JavaScript
Supports frameworks and CMSs like Laravel, WordPress

3. How does PHP differ from JavaScript?

Answer:

PHP is a server-side language; JavaScript is client-side
PHP runs on the server before output is sent to the browser
JavaScript runs in the browser and interacts with HTML elements

4. What are superglobals in PHP?

Answer: Superglobals are built-in arrays in PHP used to access variables across different scopes. Examples:

$_GET
$_POST
$_SERVER
$_SESSION
$_COOKIE

PHP OOP Interview Questions

5. What is Object-Oriented Programming in PHP?

Answer: OOP in PHP enables developers to structure code into classes and objects. It includes concepts like:

Encapsulation
Inheritance
Polymorphism
Abstraction

6. What is the difference between abstract class and interface in PHP?

Answer:

Abstract class can have both defined and undefined methods. It supports properties.
Interface can only declare methods; all methods must be public and implemented by the class.

7. What is a trait in PHP?

Answer: A trait is a mechanism for code reuse in PHP. Traits allow developers to use methods from multiple sources into a class without traditional inheritance.

Intermediate PHP Interview Questions

8. How do you connect to a MySQL database using PHP?

Answer: Using PDO (PHP Data Objects):

$pdo = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');

9. What is the use of isset() and empty() in PHP?

Answer:

isset() checks if a variable is set and not null.
empty() checks if a variable is empty (0, "", null, false, array(), etc.)

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

Answer:

== checks for value equality, allowing type conversion.
=== checks for both value and data type.

PHP Security Interview Questions

11. How do you prevent SQL Injection in PHP?

Answer: Use prepared statements with PDO or MySQLi:

$stmt = $pdo->prepare("SELECT * FROM users WHERE email = ?");
$stmt->execute([$email]);

12. What is XSS and how do you prevent it?

Answer: Cross-site scripting (XSS) occurs when attackers inject malicious scripts. Use htmlspecialchars() to escape HTML characters:

echo htmlspecialchars($user_input, ENT_QUOTES, 'UTF-8');

13. How do you protect against CSRF in PHP?

Answer: Use CSRF tokens in forms and verify them on submission. Store the token in the session and match it against the submitted value.

Advanced PHP Interview Questions

14. What are magic methods in PHP?

Answer: Magic methods are special functions prefixed with double underscores:

__construct()
__destruct()
__get(), __set()
__call()
__toString()

15. What is namespacing in PHP?

Answer: Namespaces avoid class and function name collisions. Example:

namespace App\Controllers;

class HomeController {}

16. What is autoloading in PHP?

Answer: Autoloading automatically includes class files when needed. Use spl_autoload_register() or Composer's PSR-4 autoloader.

Laravel PHP Framework Interview Questions

17. What is Laravel?

Answer: Laravel is a popular PHP MVC framework used for building scalable web applications. It offers features like:

Eloquent ORM
Routing
Blade templating
Middleware
Artisan CLI
RESTful APIs

18. What is Eloquent in Laravel?

Answer: Eloquent is Laravel's Object-Relational Mapping (ORM) that enables database queries using models and relationships.

19. How does middleware work in Laravel?

Answer: Middleware filters HTTP requests entering your application. Examples include:

Authentication checks
Role-based access control
Logging

Common Real-World PHP Coding Questions

20. Write a script to reverse a string in PHP.

function reverseString($str) {
    return strrev($str);
}

21. Write a PHP function to check if a number is prime.

function isPrime($num) {
    if ($num < 2) return false;
    for ($i = 2; $i <= sqrt($num); $i++) {
        if ($num % $i == 0) return false;
    }
    return true;
}

PHP Interview Preparation Tips

Practice common PHP programming questions
Understand OOP in PHP
Study database interactions using PDO or MySQLi
Learn form validation, session management, and security best practices
Gain working knowledge of PHP frameworks like Laravel or CodeIgniter
Familiarize yourself with REST API development in PHP
Be ready to debug code snippets during the interview