The PHP array_walk_recursive() function runs each array element in a user-defined function with the array’s keys and values as parameters in the function.

This function can work with arrays within arrays.

<?php
function my_function($value,$key) {
    echo 'The key ' . $key . ' has the value ' . $value . '<br>';
}

$a1 = array('Car 1' => 'Lamborghini', 'Car 2' => 'Ferrari', 'Car 3' => 'Maserati');
$a2 = array($a1, 'Alfa Romeo', 'Porsche');

array_walk_recursive($a2, 'my_function');
?>

The key Car 1 has the value Lamborghini
The key Car 2 has the value Ferrari
The key Car 3 has the value Maserati
The key 1 has the value Alfa Romeo
The key 2 has the value Porsche

array_walk_recursive(array, my_function, parameter, ...)