Question

All,

I can’t seem to find the answer I’m looking for using search so I’ll ask it.

I need to pull the last four digits of a credit card number out and set it into another string. It needs to account for the variances in credit card number lengths (i.e. 16 numbers or 15 numbers, etc)

i.e. if the number was “1234567890123456” I would want to set a new string as “3456”.

Thanks

Answer 1

Assuming the credit card number is stored as a string:

NSString *lastFour = [fullNumber substringFromIndex:[fullNumber length] - 4];

Assuming it’s an unsigned integer of any wide-enough type:

NSString *lastFour = [NSString stringWithFormat: @"%04u", (unsigned int)(fullNumber % 10000)];