Re: Credit card number checker?

On 16 Jul 2001 22:12:24 -0000, "Dr. Evil" <drevil@sidereal.kz> wrote: >I know that credit cards have standard formats: There's a standard >number of digits, and whether the card is Visa, MC, Amex, etc is >encoded in the number, and there is some kind of checksum, and I think >the expiration is also encoded in the number. All of this is obvious >stuff that anyone designing such a system would do. > >I'm wondering if anyone can refer me to a site that describes what >this format is, so I can write some PHP code that will check to see if >a credit card number format is correct. I don't even want to try to >run the card through my merchant account if the format is obviously >wrong. I assume that banks check the rejection rate on their merchant >accounts, and too many bogus cards would not look good. Right. Especially since they don't have the card physically present, online merchants should sanity check the card number before submitting it for authorization. Even honest customers could make a typing mistake that renders their input completely bogus. See page 2 of: http://perl.about.com/library/weekly/aa073000a.htm