#24 CC validation formula

[Richard Archer]

From: Lindsay Haisley

Here's a neat little piece which I put together to
check credit card
numbers. The algorithm for doing this is based on
what's called the LUHN
formula which you can find lots of places such as
<http://www.webopedia.com/TERM/L/Luhn_formula.html>
although credit card
companies won't tell you what it is :-). This might
make a nice add-on to
the cart class, although it's certainly functionally
peripheral to operation
of the class.

[nathan hruby]

Logged In: YES
user_id=19736

Umm.. There's no patch attached to this tracker Item :)

Anyone got one? If not I'm closing the patch...

[Richard Archer]

luhn verification code

[Richard Archer]

Logged In: YES
user_id=279311

I don't know what's going on here... I reckon there's at
least 4 notes I've posted to these trackers that have gone
missing.

Anyway, here's the LUHN script.