- var_dump: documentation ( source)
- array_udiff: documentation ( source)
<?php
$a1 = array('red');
$a2 = array('red', 'blue');
$diff = array_udiff($a1, $a2,
function($a, $b) {
if($a === $b) {
return 0;
}
else {
return -1;
}
});
var_dump($diff);