C/C++平台区分宏定义

#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__)
    #define OS_WINDOWS
#elif defined(__CYGWIN__) || defined(__CYGWIN32__)
    #define OS_CYGWIN
#elif defined(linux) || defined(__linux) || defined(__linux__)
    #ifndef OS_LINUX
        #define OS_LINUX
    #endif
#elif defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__)
    #define OS_MACOSX
#elif defined(__FreeBSD__)
    #define OS_FREEBSD
#elif defined(__NetBSD__)
    #define OS_NETBSD
#elif defined(__OpenBSD__)
    #define OS_OPENBSD
#else
// TODO Add other platforms.
#endif