- array_walk: documentation ( source)
<?php
$array_1 = array('something1', 'foo');
$array_2 = array('something3', 'bar');
$array_3 = array();
$array_4 = array('something1', 'foobar');
array_walk(array($array_1,$array_2,$array_3,$array_4),function(&$value, $key){
});