Top 30 PHP Interview Questions and Answers (Beginner Level – 2025 Edition)

🔹 1. What is PHP and what does it stand for?

Answer:
PHP stands for Hypertext Preprocessor. It’s an open-source, server-side scripting language designed for web development. It runs on the server and generates dynamic HTML content.

🔹 2. What are the main features of PHP?

Answer:

• Open-source & free
• Cross-platform (Windows, Linux, macOS)
• Easy to learn
• Integrates well with databases (like MySQL)
• Large community and lots of frameworks

🔹 3. What is the latest PHP version as of 2025?

Answer:
As of mid-2025, PHP 8.3 is the latest stable version. PHP 8.4 is expected to release later this year.

🔹 4. What's the difference between echo and print in PHP?

Answer:

• echo can take multiple arguments and is slightly faster
• print can only take one argument and always returns 1 (so it can be used in expressions)

echo "Hello", " World!";
print "Hello World!";

🔹 5. How do you declare a variable in PHP?

Answer:

$name = "John";
$age = 25;

Variables in PHP start with a $ sign, and types are inferred (loosely typed).

🔹 6. What are the different data types in PHP?

Answer:

• String
• Integer
• Float (double)
• Boolean
• Array
• Object
• NULL
• Resource

🔹 7. What is a constant and how do you define one?

Answer:

define("SITE_NAME", "MyBlog");

Constants are declared using define() or const and cannot be changed after definition.

🔹 8. What is type hinting in PHP?

Answer:
Type hinting lets you specify data types for function arguments, return values, and class properties.

function greet(string $name): string {
    return "Hello, $name!";
}

🔹 9. What are Union Types in PHP?

Answer:
Union types allow a variable to accept more than one type.

function showId(int|string $id) {
    echo $id;
}

Introduced in PHP 8.0+.

🔹 10. What is a constructor in PHP?

Answer:
A special method (__construct) that gets called automatically when a new object is created.

class User {
    public function __construct() {
        echo "User created!";
    }
}

🔹 11. What are PHP Attributes?

Answer:
Attributes (introduced in PHP 8) allow metadata to be added to classes, functions, or properties.

#[Example]
class Test {}

🔹 12. What are Enums in PHP?

Answer:
Enums allow defining a fixed set of possible values.

enum Status {
    case Active;
    case Inactive;
}

Introduced in PHP 8.1+.

🔹 13. How do you write an if-else statement in PHP?

$age = 18;
if ($age >= 18) {
    echo "Adult";
} else {
    echo "Minor";
}

🔹 14. How is a switch-case used in PHP?

switch ($color) {
    case 'red':
        echo "Red!";
        break;
    case 'blue':
        echo "Blue!";
        break;
    default:
        echo "Unknown";
}

🔹 15. How do you define and access an array in PHP?

$colors = ["red", "blue", "green"];
echo $colors[1]; // blue

🔹 16. What is the difference between indexed and associative arrays?

Answer:

• Indexed: Keys are numbers
• Associative: Keys are strings

$assoc = ["name" => "John", "age" => 25];

🔹 17. How do you connect PHP to a MySQL database?

$conn = mysqli_connect("localhost", "root", "", "mydb");

🔹 18. What is the use of isset() and empty()?

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

🔹 19. What are PHP sessions?

Answer:
Sessions are used to store user data across multiple pages (e.g., login sessions).

session_start();
$_SESSION['user'] = "John";

🔹 20. What’s the difference between GET and POST methods in forms?

• GET: Appends data to URL, less secure
• POST: Sends data invisibly, better for sensitive info

🔹 21. How do you handle errors in PHP?

try {
    // risky code
} catch (Exception $e) {
    echo $e->getMessage();
}

🔹 22. What are traits in PHP?

Answer:
Traits let you reuse code across multiple classes.

trait Logger {
    public function log($msg) {
        echo $msg;
    }
}

🔹 23. What are superglobals in PHP?

Answer:
Built-in variables accessible globally:

• $_GET, $_POST, $_SESSION, $_COOKIE, $_FILES, $_SERVER, $_ENV, $_REQUEST

🔹 24. What is the nullsafe operator?

Answer:

$user?->profile?->avatar

Prevents null errors by safely chaining object properties (introduced in PHP 8.0).

🔹 25. What is Composer in PHP?

Answer:
Composer is the dependency manager for PHP, used to install libraries and manage packages.

composer require vendor/package

🔹 26. What are PSRs in PHP?

Answer:
PHP Standard Recommendations (PSRs) are coding standards (e.g., PSR-4 for autoloading, PSR-12 for code style).

🔹 27. What are anonymous functions or closures?

Answer:

$square = function($x) {
    return $x * $x;
};

🔹 28. How do you include one PHP file in another?

include 'header.php';
require 'config.php';

• include: gives a warning if the file is missing
• require: causes a fatal error

🔹 29. What is the difference between == and ===?

• ==: Compares values only
• ===: Compares values and types

1 == "1" // true  
1 === "1" // false

🔹 30. How do you sanitize user input in PHP?

$name = htmlspecialchars($_POST['name']);

Sanitization and validation are critical to prevent XSS or SQL injection.

✅ Bonus Tips for Interviews

• Learn to explain "why" behind code, not just syntax.
• Practice short coding exercises (FizzBuzz, palindromes, etc.).
• Show an understanding of basic security and performance concepts.