$_post and array question

Best readers, //PHP version: 4.3.6 I have question concerning the following issue: I have a HTML input element of the type check. <input type="checkbox" name="test_arr[]"> let assum this checkbox is unchecked. The checkbox is part of a form. Now we gonna submit this form (post) and gonna catch the POST variable test_arr like this: $arr_test = $_POST["test_arr"]; This will result in a novice error "Undefined index: " Of course because test_arr does not exist. It's unchecked. Now we gonna do the following: We immediately put the $_POST["test_arr"] into a function and then we assign $_POST["test_arr"] to $arr_test like this: functionX($_POST["test_arr"]) $arr_test = $_POST["test_arr"]; Knowing that $_POST["test_arr"]) does not exist.. this code will not result in a error. Is this a bug,error,etc? Should this not also produce a novice error? Thanks for reading, Amon