- var_dump: documentation ( source)
- array_udiff: documentation ( source)
<?php
$a = ["1","2"];
$b = ["2",3=>[]];
$out = array_udiff($a, $b, function($c, $d) {
static $i = 0;
echo ++$i. @": $c != $d= ".$c != $d.PHP_EOL;
return $c != $d;
});
var_dump($out);