PHP Functions

User-defined functions, types and arrow functions.

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Define a function with function name($param) { ... }.

Default values: function greet($name = "Guest")
Type declarations: function add(int $a, int $b): int
Named arguments (PHP 8): greet(name: "Ali")
Pass by reference with &: function addOne(&$n)
Arrow functions: fn($x) => $x * 2

Add declare(strict_types=1); at the top of a file to make type checks strict.

Key Takeaways: PHP Functions

Mastering PHP Functions helps you write clean and reliable PHP code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.

PHP Functions Code Example

PHP

<?php
declare(strict_types=1);

function add(int $a, int $b): int {
    return $a + $b;
}

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

$double = fn($n) => $n * 2;

echo add(5, 7) . "<br>";
echo greet() . "<br>";
echo greet(greeting: "Assalam-o-Alaikum", name: "Usman") . "<br>";
echo $double(21);

Output

12
Hello, Guest!
Assalam-o-Alaikum, Usman!
42

Run this example on your own computer. The "Get Started" lesson shows how to set it up.

PHP Functions Practice Exercises

Check what you learned in “PHP Functions”.

/ 2 solved

Fill in the blank

Declare the return type of the function.

function add(int $a, int $b) { return $a + $b; }

✓ Correct! Not quite. Try again.

Multiple choice

Which is a PHP arrow function?

fn($x) => $x * 2 function($x) -> $x * 2 ($x) => { $x * 2 } lambda $x: $x * 2

✓ Correct! Not quite. Try again.

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PHP Functions

💡 Key Takeaways: PHP Functions

PHP Functions Code Example

PHP Functions Practice Exercises

Key Takeaways: PHP Functions