MagGem: Validating Credit Card Numbers
Posted February 16 2011
Credit card validation is one of those things that you don't pay much attention to until you need to do it. I'm not talking about processing payments - most of us use services for that - but about that first check that verifies the card number itself is valid, as a guard against incorrectly entered data.
There is a standard methodology for card number validation: it's called the Luhn algorithm. It's basically a checksum formula, and is used for credit card numbers, US National Provider Identifier numbers and Canadian Social Insurance numbers.
Back in 2004 Abe Jimenez needed to do that kind of validation, and to his surprise he couldn't find a Clarion version of the code. So he wrote one.
Watch the MagGem in ClarionLive Webinar #94
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From the archives
Making Sense of ABC's ErrorClass - Part 1
11/21/2000 12:00:00 PM
If there's one part of ABC that consistently draws fire, it's ErrorClass. In this three part series, Russ Eggen puts on his flak jacket and steps out into no man's land to explain what ErrorClass is all about, why it's good, and what you can do with it.