On Wed, 28 Nov 2001 23:25:14 -0500, "Paris Lundis" <[EMAIL PROTECTED]> wrote:
>Here's the deal: > >it is a mod-10 formula... based on the length... so on some it is odd digit >math, others it is even... > >3xxx - AMEX >4xxx - Visa >5xxx - MasterCard >6xxx - Discover > >the formula is widely available and hasn't changed in 20 years.. it is 2nd >grade math.... It's been ages since I wrote up and cf or javascript code for it but, to expand: I believe it was called the "lun"(?) algorithm. Basically it does NOT validate the credit card number -- you have to talk to a cc gateway for that. It's purpose was to generate a long number that was resistant to typos by data entry clerks. If you mistype a single digit in cc number there's a pretty good chance the lun alg will will report it's an invalid cc number. That's all all it does -- catch simple typos. --min ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Get the mailserver that powers this list at http://www.coolfusion.com FAQ: http://www.thenetprofits.co.uk/coldfusion/faq Archives: http://www.mail-archive.com/cf-talk@houseoffusion.com/ Unsubscribe: http://www.houseoffusion.com/index.cfm?sidebar=lists
