问在运行时确定操作系统？

EN

char *get_os_name (void);

#ifdef _LINUX
    char *get_os_name (void)
    {
         static nm [1000];
         FILE *f = fopen ("/proc/version", "r");
         if (!f  &&  !fgets (nm, sizeof nm, f))
               return NULL;  /* could next try uname(), etc. */
         fclose (f);
         return nm;
    }
#endif

#ifdef _WIN32
    char *get_os_name (void)
    {
         OSVERSIONINFO   vi;

         memset (&vi, 0, sizeof vi);
         vi .dwOSVersionInfoSize = sizeof vi;
         GetVersionEx (&vi);
         switch (vi.dwPlatformId)
         {
         case VER_PLATFORM_WIN32_NT:  return "Win32";
         ...
         }
    }
#endif