There is a credit card validating class on phpclasses.org under e-commerce.
"Martin Towell" <[EMAIL PROTECTED]> wrote in message
> Try this:
> function do_mod_10($num)
> // The Luhn formula works right to left, so reverse the number.
> $num = strrev($num);
> $total = 0;
> for ($i = 0, $j = 1; $i < strlen($num); $i++, $j=3-$j)
> $digit = $num[$i] * $j;
> if ($digit > 9) $digit -= 9;
> $total += $digit;
> return ($total % 10 == 0);
> -----Original Message-----
> From: Mark McCulligh [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, July 24, 2002 10:47 AM
> To: [EMAIL PROTECTED]
> Subject: [PHP] Re: Credit card checks?
> You could use an algorithms called mod10. Both Visa, MasterCard and I
> most other credit cards use the mod10 algorithm. A credit card must pass
> mod10 test to be a valid number(Like a Regular Expression test). It won't
> tell you if the number exist, but it will tell you if it could exist. I
> also know the mod10 is used for Canadian Social Security numbers (SIN).
> Unfortunately I have never seen a PHP function for it, I only used mod10
> a language called Uniface by Compuware. I know there is another name for
> it also, but I can't remember it right now.
> It is a great test, someone just typing in numbers at random will have a
> terrible time guessing a number right. I have never seen someone do it
> Then you can use the first character of the number to test the card type.
> I will see if I can locate the algorithm and email it too you.
> "Jas" <[EMAIL PROTECTED]> wrote in message
> [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > Just wondering if anyone has come across the need to develop a class to
> > a string of numbers based on a credit card type. If you have where
> > be able to get information on what string of numbers is consistent with
> > of the different credit cards? Any help would be appreciated!
> > Jas
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