--TEST-- SPL: spl_object_id() --FILE-- <?php var_dump(spl_object_id(new stdClass)); var_dump(spl_object_id(42)); var_dump(spl_object_id()); $a = new stdClass(); var_dump(spl_object_id(new stdClass) === spl_object_id($a)); ?> --EXPECTF-- int(%d) Warning: spl_object_id() expects parameter 1 to be object, int given in %sspl_object_id.php on line %d NULL Warning: spl_object_id() expects exactly 1 parameter, 0 given in %sspl_object_id.php on line %d NULL bool(false)