转自：http://www.cnblogs.com/SunWentao/archive/2008/12/26/1363128.html
#ifdef _MSC_VER_ // for MSVC
#define forceinline __forceinline
#elif defined __GNUC__ // for gcc on Linux/Apple OS X
#define forceinline __inline__ __attribute__((always_inline))
#else
#define forceinline
#endif