Hi Hajo, Normal promotion rules apply. You have both: 1 << 31 (which is a signed int) 0xFFFFFFFF (which is an unsigned int) PRESUMING that int is 32-bit, and long is 64-bit... The use of both of those together makes the enum values signed long int, in C++. (Not so in C.) I strongly recommend you avoid mixing signed int and unsigned int values in your enum. Therein lies the path to madness. For unsigned bias, use: 1U << 31 // explicit unsigned (unsigned)1 << 31 // explicit unsigned 0xFFFFFFFF // implicit unsigned (unsigned)0xFFFFFFFF // explicit unsigned 0xFFFFFFFFU // explicit unsigned ~0U // explicit unsigned For signed bias, use: 1 << 31 // signed int (int)0xFFFFFFFF // explicit cast to signed int ~0 // signed int Also be aware that if your "1 << 31" goal is to set the high bit, then your code is not portable. If the platform has 64-bit int, you will instead be setting a middle bit. If the platform has 16-bit int, such a shift is undefined behavior. Consider instead: 1 << (((CHAR_BIT) * sizeof(int)) - 1) // CHAR_BIT from <climits> ~0 HTH, --Eljay
