(PHP 5)
array_udiff — Computes the difference of arrays by using a callback function for data comparison
Computes the difference of arrays by using a callback function for data comparison. This is unlike array_diff() which uses an internal function for comparing the data.
array1The first array.
array2The second array.
data_compare_funcThe callback comparison function.
The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.
   Returns an array containing all the values of array1
   that are not present in any of the other arguments.
  
Example #1 array_udiff() example
<?php
class cr {
    private $priv_member;
    function cr($val)
    {
        $this->priv_member = $val;
    }
    static function comp_func_cr($a, $b)
    {
        if ($a->priv_member === $b->priv_member) return 0;
        return ($a->priv_member > $b->priv_member)? 1:-1;
    }
}
$a = array("0.1" => new cr(9), "0.5" => new cr(12), 0 => new cr(23), 1=> new cr(4), 2 => new cr(-15),);
$b = array("0.2" => new cr(9), "0.5" => new cr(22), 0 => new cr(3), 1=> new cr(4), 2 => new cr(-15),);
$result = array_udiff($a, $b, array("cr", "comp_func_cr"));
print_r($result);
?>
The above example will output:
Array
(
    [0.5] => cr Object
        (
            [priv_member:private] => 12
        )
    [0] => cr Object
        (
            [priv_member:private] => 23
        )
)
Note: Please note that this function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using array_udiff($array1[0], $array2[0], "data_compare_func");.