Weryfikacja numeru PWZ

pwz.php

<?php
function check_pwz_number ($number)
{
	if (strlen($number) != 7 || preg_match('/^0+$/', $number)) return false;
	$c = (int)$number[0];
	$n = substr($number, 1);
	$s = 0;
	for ($i = 1; $i <= 6; $i ++) $s += (int)$n[$i - 1] * $i;
	return ($s % 11) == $c ? true : false;
}