Category : Pascal Source Code
Archive   : VCARD.ZIP
Filename : VC.DOC

Hello:

I hope that you can find a use for my little program VC.EXE
and hopefully also the included source code. What VC does is
check and validate credit card numbers against the internally
encoded 'Modulo-10 Check digit' information that is in every
credit card. I wont go into details here about how that works
the source should be adequate documentation. If anyone wants
that drop me a line and we'll see what we can do!

To use VC just type 'VC' at the DOS command line, and then
answer the prompt for a card number with a valid one. You can
include the hyphens or spaces in the card number, but it is
not necessary to do so.

To use VC in one of your Turbo Pascal programs just include
the name Vericard in your 'uses' statement and then call the
routine as follows:


Program Check_4_Bogus;

Uses dos,crt,Vericard;

var
card : string[18];
k : char;

Begin
clrscr;
fillchar(Card,18,#0);
Writeln('VC: Integer Modulo-10 Visa/Mastercard/Amex Check-Digit');
Writeln(' verification routine. (c) 1990 Daniel J. Karnes');
Writeln;
Write(' Please enter a Credit Card number: ');
Readln(card);

writeln;
writeln;

k:=Vc(card); { <--- This calls VC up }

case k of

#0 : Writeln(' Could NOT verify this number with any card type.');
'3' : Writeln(' Card was verified as a valid American Express Card Number.');
'4' : Writeln(' Card was verified as a valid VISA Card Number.');
'5' : Writeln(' Card was verified as a valid Mastercard Number.');

end;

end.


VC will return a character that is equal to the first character in the
card number or a null if the card is invalid in any way. VC should work
with any credit card, but in this example it is only testing for Visa,
M/C, and Amex.

If there are any problems that you find with this program please report
them to me so that I can do something about it. Also if you use this, I
do ask that you understand you are doing so at your own risk!

If you find this program useful and continue to use it I would truly be
thankful if you would send me $5.00 or WHATEVER you feel this little
program is worth. If you are using this is a business situation the $5
is mandatory. Although I have been working in the field for a long
time this is the first PD program that I have asked this of. If I get
(any?) response I will continue to develop this and other concepts in
the near future. Please enjoy, and I do hope this is of use to you!


Daniel J. Karnes
1 Baron Park #20
Burlington, MA 01803

CIS: 71240,3407