Using array_walk_recursive() to Apply a User Function Recursively to Array Elements in PHP

array_walk_recursive() applies a user-defined callback function to each element of an array, recursively traversing nested arrays.

Parameters

input : The array to be processed.

funcname : The callback function. It typically receives the value as the first argument and the key as the second; pass the value by reference if the function should modify the original array.

userdata (optional): Additional data passed as a third argument to the callback.

Return value : Returns TRUE on success, FALSE on failure.

Example

<?php
$sweet = array('a' => 'apple', 'b' => 'banana');
$fruits = array('sweet' => $sweet, 'sour' => 'lemon');

function test_print($item, $key) {
    echo "$key holds $item
";
}

array_walk_recursive($fruits, 'test_print');
?>

Output

a holds apple
b holds banana
sour holds lemon