In message <Pine.SOL.4.10.10005161427280.1631-100000@imsp234.hkstar.com>, Fong 
Siu Lung Gordon writes:
>Yes, 14-character. My method is to individually cut the 14-character into
>14 tokens and calculate the check digit from these tokens.  It works.  The
>problem is I have to calculate the check digit for a series of borrow card
>not just one and I don't to type it again and again.  The method I though
>of is to make a copy the start borrow card and increment by 1 each time.
>Then re-calculate the check digit and the new borrow card number.  The
>probelm is max int of my system (i386) is largest enough to hold the
>14-charater digit.  That is the point.

I think you should try asking about this in one of the comp.lang.c groups,
you'd probably get some pretty good answers.

-s