Not sure whether this answer is of use, but I'll write it anyway. (I like to see myself write :-D.) According to the manpages of sprintf() on my Linux box, the 'L' modifier is only used in conjunction with long double. If you want to use the correct modifier for ints, one uses 'll' (ell-ell). And forgive me if I'm wrong here (I never use long longs), but shouldn't the declaration read 'long long int number'? Or does StormC understand that it is an int without explicitly writing it down?