- var_dump: documentation ( source)
- array_udiff: documentation ( source)
<?php
$a= [['a', 10], ['b', 11], ['c', 12], ['d', 13]];
$b = [['k', 21], ['l', 22], ['m', 23]];
$diff = array_udiff($a, $b, function($o1, $o2) {
echo 'comparing ' . $o1[0] . ', ' . $o2[0];
return $o1[1] - $o2[1];
});
var_dump($diff);