Master PHP Functions: Defining, Passing, Looping, and Returning Arrays

In PHP programming, arrays are a fundamental data type that store multiple values as key‑value pairs, and they are frequently used when writing custom functions.

1. Defining an array

In PHP you can define an array with the array() function. For example:

$my_array = array(1, 2, 3);

You can also define an array inside a function:

function my_function() {
    $my_array = array(1, 2, 3);
}

2. Passing an array as a parameter

To operate on an array inside a function, pass it as an argument:

function my_function($my_array) {
    // operate on $my_array
}

This example defines my_function and passes $my_array to it.

3. Traversing an array

PHP provides two common ways to iterate over an array.

Using a for loop:

function my_function($my_array) {
    for ($i = 0; $i < count($my_array); $i++) {
        echo $my_array[$i] . "<br>";
    }
}

Using a foreach loop:

function my_function($my_array) {
    foreach ($my_array as $value) {
        echo $value . "<br>";
    }
}

4. Returning an array

After modifying an array, return it with the return statement:

return $my_array;

5. Full example

The following code demonstrates defining, passing, iterating, modifying, and returning an array within a PHP function:

function my_function($my_array) {
    for ($i = 0; $i < count($my_array); $i++) {
        $my_array[$i] = $my_array[$i] * $my_array[$i];
    }
    return $my_array;
}
$my_input_array = array(1, 2, 3);
$my_output_array = my_function($my_input_array);
foreach ($my_output_array as $value) {
    echo $value . "<br>";
}

Summary

Defining, passing, iterating, and returning arrays in PHP functions are common operations; choosing the appropriate loop (for or foreach) and correctly handling the array ensures efficient and reliable PHP applications.