sizeof(int) == sizeof(long)

sizeof(int) == sizeof(long)

Data that fits in an int or long on 32-bit systems will fit in an int on 64-bit systems. Expansion, in this case, has no visible effect. Problems may occur, however, where an unsigned int actual parameter is passed to a long (signed or unsigned) formal parameter without benefit of an ANSI prototype. In this case, the unsigned value is implicitly sign-extended in the register, and therefore is misinterpreted in the callee if the sign bit was set.