CODEWITHSUNDEEP
winapi
Josh Wallace
Josh Wallace

Reputation: 63

C++ Win32 PostQuitMessage(0) not working? CPU @ 100%

OK so I have my main window procedure (simplified):

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_CREATE:
        {
            if(!loadFiles())
                SendMessage(hwnd, WM_CLOSE, 0, 0);
        }
        break;

        case WM_CLOSE:
            DestroyWindow(hwnd);
            return 0;
        break;

        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
        break;

        default:
            return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}

loadFiles() is a function to read some text files. If the files are missing, it posts an error message and then returns false. I handle this by sending the WM_CLOSE message, which sends WM_DESTROY? The program calls PostQuitMessage(0) and.. nothing. The process is still sitting in background, now using 100% CPU on core 1. Here is my message loop :

MSG Msg;
while(GetMessage(&Msg, NULL, 0, 0) > 0)
{
    TranslateMessage(&Msg);
    DispatchMessage(&Msg);
}
return Msg.wParam;

Very simple, I've looked around and seen people using all kinds of different loops, most with PeekMessage() function.. its worth noting I have several child windows containing different controls, I show and hide them when the user selects different tabs, but I don't think it matters because PostQuitMessage(0) is supposed to post WM_QUIT to the message queue, which destroys the child windows aswell right? Any help? Thanks

Upvotes: 3

Views: 1599

Answers (1)

Werner Henze
Werner Henze

Reputation: 16726

According to MSDN WM_CREATE is sent during CreateWindow. So you are destroying the window right during creation. I am not sure that this is supposed to work. Also, why so complicated? The documentation says

If an application processes this message, it should return zero to continue creation of the window. If the application returns –1, the window is destroyed and the CreateWindowEx or CreateWindow function returns a NULL handle.

So just return -1 in case loadFiles() fails and handle CreateWindow returning NULL accordingly.

Upvotes: 3

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