From: James Edward Gray II <james@...>
Date: 2007-04-29T00:43:01+09:00
Subject: Re: [QUIZ] Checking Credit Cards (#122)

On Apr 28, 2007, at 7:43 AM, Christoffer Lern� wrote:

> On Apr 27, 2007, at 23:06 , James Edward Gray II wrote:
>
>> On Apr 27, 2007, at 3:10 PM, anansi wrote:
>>
>>> James Edward Gray II wrote:
>>>> On Apr 27, 2007, at 12:58 PM, Matthew Moss wrote:
>>>>> So is a card number like "4012 3456 7890" a valid Unknown, or  
>>>>> an invalid Visa?
>>>> Visa Invalid
>>>> Always match the type first.
>>>
>>> Nope thats no Visa number but a unknown one. Visa Cards have a  
>>> certain length (13 or 16) and if that length doesn't fit  
>>> (Matthew's number here had just 12 digits)it's unknown :)  
>>> otherwise the length would be obsolete don't you think?
>>> Both length and startingbytes have equal weight in the decision  
>>> wether a card belongs to a known Company or not.
>>
>> You are right.  I didn't read well.  It's Unknown.
>>
>> James Edward Gray II
>
> Do we display Valid/Invalid for unknown cards?
>
> - And by the way: 4012 3456 7890 isn't valid is it? So should that  
> not be "invalid Unknown" or "invalid Visa"?

I would go ahead and display Valid/Invalid normally.  That way people  
can use the program on cards we didn't cover, as long as they conform  
to the standard.

James Edward Gray II