Operating System Bit Size Detection using C/C++

#ifdef __GNUC__
    #include "stdint.h"
    #if INTPTR_MAX == INT32_MAX
        #define __ENV32
        #define __SYS_BITS 32
    #elif INTPTR_MAX == INT64_MAX
        #define __ENV64
        #define __SYS_BITS 64
    #else
        #define __ENV_UNKNOWN
        #define __SYS_BITS 0
    #endif
#elif defined(_WIN32)
    #define __ENV32
    #define __SYS_BITS 32
#elif defined(_WIN64)
    #define __ENV64
    #define __SYS_BITS 64
#else
    #define __SYS_BITS (sizeof(void*)*8)
#endif