Checking if your game has been started multiple times

[Laurens]

Thought I'd share this bit of code with you I found quite useful. It basically checks if your game has already been started to prevent players from going bananas on your executable. If your game has already been started, it brings it to the front.

 

const bool Application::IsOnlyInstance(const std::string title) const {
   HANDLE h = CreateMutex(0, true, title.c_str());

   if (GetLastError() != ERROR_SUCCESS) {
       HWND hWnd = FindWindow(title.c_str(), 0);

       if (hWnd != 0) {
           ShowWindow(hWnd, SW_SHOWNORMAL);
           SetFocus(hWnd);
           SetForegroundWindow(hWnd);
           SetActiveWindow(hWnd);
       }

       return false;
   }

   return true;
}

 

Title refers to the caption in the window's title bar so you do need to call this after having called SetAppTitle(...).

 

From GameCode: http://code.google.com/p/gamecode3/

 

Cheers!