Sams Teach Yourself CGI in 24 Hours, Second Edition

Q&A

Q1:	You mentioned validating credit card numbers with checksums earlier; where can I find out more?
A1:	There is a formula, called the Luhn check, that you can apply to credit card numbers to check for mistyped numbers. Information on using the Luhn check can be found at http://www.beachnet.com/~hstiles/cardtype.html You can also use the Business::CreditCard Perl module to verify credit card numbers using the checksum formula for each credit card type rather than writing the code to do it yourself.