Message This integer constant value will be given the type unsigned long int. This is compatible with the C89 standard and older compilers. The C99 standard requires this to be a signed long long int. Description With the introduction of the long long int type, the C99 standard changed the rules for how the type of certain integer constants are determined. Unsuffixed decimal constants which are too large for long int, but could fit in an unsigned long int are given the type long long int in C99. Prior to C99 these would be given unsigned long int type. User Action Be aware of this difference.