a simple PHP function to flatten an arbitrarily nested array.

flatten_array.php

$a = array('a', 'b', array(array(array('1'), '2', '3')), array(array('xyz')));

function make_flat($array,$result) {
	for($i = 0; $i <= count($array); $i++) {
		if(is_array($array[$i])) {
			$result = make_flat($array[$i], $return);
		}
		else {
			if(isset($array[$i])) {
				$result[] = $array[$i];
			}
		}
	}
	return $result;
}

$res = make_flat($a, array());