C语言_跨平台宏定义

C语言跨平台宏定义

#ifdef 表示宏是否有定义，如果宏有定义则执行，否则不执行。后面常跟#else和#endif
#if 后跟常量整数表达式，如果表达式为非零值，则表达式为真，如果没有define（宏没有定义），也不不执行。后面常跟#elif #else #endif

#ifdef _WIN32
   //define something for Windows (32-bit and 64-bit, this part is common)
   #ifdef _WIN64
      //define something for Windows (64-bit only)
   #else
      //define something for Windows (32-bit only)
   #endif
#elif __APPLE__
    #include "TargetConditionals.h"
    #if TARGET_IPHONE_SIMULATOR
         // iOS Simulator
    #elif TARGET_OS_IPHONE
        // iOS device
    #elif TARGET_OS_MAC
        // Other kinds of Mac OS
    #else
    #   error "Unknown Apple platform"
    #endif
#elif __ANDROID__
    // android
#elif __linux__
    // linux
#elif __unix__ // all unices not caught above
    // Unix
#elif defined(_POSIX_VERSION)
    // POSIX
#else
#   error "Unknown compiler"
#endif