array_udiff Computes the difference of arrays by using a callback function for data comparison &reftitle.description; arrayarray_udiff arrayarray1 arrayarray2 array ... callbackdata_compare_func 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. &reftitle.parameters; array1 The first array. array2 The second array. data_compare_func The callback comparison function. The user supplied callback function is used for comparison. It 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. &reftitle.returnvalues; Returns an array containing all the values of array1 that are not present in any of the other arguments. &reftitle.examples; 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); ?> ]]> &example.outputs; cr Object ( [priv_member:private] => 12 ) [0] => cr Object ( [priv_member:private] => 23 ) ) ]]> &reftitle.notes; 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");. &reftitle.seealso; array_diff array_diff_assoc array_diff_uassoc array_udiff_assoc array_udiff_uassoc array_intersect array_intersect_assoc array_uintersect array_uintersect_assoc array_uintersect_uassoc