I do this way. . without open mutex

mutex = ::CreateMutex(NULL, true, mutexName);
       if (  GetLastError() == ERROR_ALREADY_EXISTS )
       {
            ::MessageBox (NULL,"Attempt to run second instances ", "Application", MB_ICONSTOP);
            return 0;
       }


무한질주 님이 쓰신 글 :
: 아래와 같이 한번 해보심이....
:
: mutex = OpenMutex(MUTEX_ALL_ACCESS, false, mutexName);