I've coped with this by writing my own form parser (in defiance of all the good advice here). I n my defence, it was when I first started writing in Perl and I hadn't heard of modules!

Anyway, I am replying to give you a completely different take on this. Personally, I loathe credit card forms where you have to enter the different elements into different fields. I regard tht as user-hostile. The credit card captures I write allow you to enter the whole number into one field and delimit the sections with spaces, hyphens or not at all.

Same goes for the expiry date. Either offer two drop downs for month and year (remembering to have the years move forward automatically relative to the current year) or a single field that will accept dates as 2/02, 2/2002, 0202, 02/02, 02.02 02 02, etc etc. (Drop downs are a lot easier!)