Mine

while ($field = each($_POST)) {
		if (empty($field['value'])) unset(current($_POST));
		}

	$testcase = array("address", "phone", "email", "address", "city", "state", "zip");
	$postkeys = array_keys($_POST);
	$missingfields = array_diff($testcase, $postkeys);
	print_r $missingfields;
}