Get all keys from a multidimensional array From http://stackoverflow.com/questions/11234852/how-to-get-all-the-key-in-multi-dimensional-array-in-php

get_array_key_multi.php

<?php
function array_keys_multi(array $array)
{
    $keys = array();

    foreach ($array as $key => $value) {
        $keys[] = $key;

        if (is_array($array[$key])) {
            $keys = array_merge($keys, array_keys_multi($array[$key]));
        }
    }

    return $keys;
}
?>