Use this:
#include <stdint.h> const int64_t myvar = INT64_C(0xFF00000000000000);
Note, <stdint.h> is part of C99, it's in GCC 3.3 (maybe earlier), and you can use <stdint.h> in your C++ program. That's <stdint.h> in C++, not <cstdint> as one my presuppose ... not yet at least.
HTH, --Eljay
