<?
function luhn_check($number) {
$number=preg_replace('/\D/', '', $number);
$number_length=strlen($number);
$parity=$number_length % 2;
$total=0;
for ($i=0; $i<$number_length; $i++) {
$digit=$number[$i];
if ($i % 2 == $parity) {
$digit*=2;
if ($digit > 9) {
$digit-=9;
}
}
$total+=$digit;
}
return ($total % 10 == 0) ? TRUE : FALSE;
}
?>