Creating a Window

Ok i have decent experience with c++, however
it was consoel use, i finally decided that i understood enough
to start a win32 windowed application. So i got a tutorial
and got started, a little into the tutorial everything going
great and it running like i expected, however the problem
comes in when i close the program. The window
disappears when i press the X, but the process remains
in the task manager? Based on the following code
any idea why it doesnt quit running even though
the window disappears?

Code:

---

#include <windows.h>
#include "resource.h"

LRESULT CALLBACK WndProcedure(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstace, LPSTR lpCmdLine, int nCmdShow)
{
        HWND hWnd;
        MSG Msg;
        WNDCLASSEX WndClsEx;
        const char ClsName[] = "BasicApp";
        const char WndName[] = "A Simple Window!";
        WndClsEx.cbSize = (sizeof(WNDCLASSEX));
        WndClsEx.style = CS_HREDRAW | CS_VREDRAW;
        WndClsEx.lpfnWndProc = WndProcedure;
        WndClsEx.cbClsExtra = 0;
        WndClsEx.cbWndExtra = 0;
        WndClsEx.hIcon = LoadIcon(NULL, IDI_INFORMATION);
        WndClsEx.hCursor = LoadCursor(hInstance, MAKEINTRESOURCE(IDC_CURSOR1));
        WndClsEx.hbrBackground = (HBRUSH)GetStockObject(LTGRAY_BRUSH);
        WndClsEx.lpszMenuName = NULL;
        WndClsEx.lpszClassName = ClsName;
        WndClsEx.hInstance = hInstance;
        WndClsEx.hIconSm = LoadIcon(NULL, IDI_INFORMATION);

        RegisterClassEx(&WndClsEx);

        hWnd = CreateWindow(ClsName, WndName, WS_OVERLAPPEDWINDOW,
                CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
                CW_USEDEFAULT, NULL, NULL, hInstance, NULL);
        if(!hWnd)
        {
                return 0;
        }
        ShowWindow(hWnd, SW_SHOWNORMAL);
        UpdateWindow(hWnd);
        while( GetMessage(&Msg, hWnd, 0, 0))
        {
                TranslateMessage(&Msg);
                DispatchMessage(&Msg);
                Sleep(1);
        }


        return 0;
}

LRESULT CALLBACK WndProcedure(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
        switch(uMsg)
        {
                case WM_DESTROY :       
                                                {
                                                        PostQuitMessage(WM_QUIT);
                                                        break;
                                                }
                default                        :       
                                                {
                                                        return DefWindowProc(hWnd, uMsg, wParam, lParam);
                                                }
        }
        return 0;
}

---

EDIT : I didn't add the soruce for resource.h because the
problem was there before i added it.

Funny thing about GetMessage(), it retuns a BOOL or -1.

http://msdn.microsoft.com/library/de...getmessage.asp

Use the message loop construct shown in that link.

gg

Thanks that worked, just out of curiosity, if the if statment
when i check for the error, fi the error comes up,
should i just call GetMessage again, or should i do something else?

I've always treated -1 and FALSE the same - the message loop stops.

In your case, GetMessage() was returning -1 once the hWnd parameter was no longer valid. In other words, the window handle became invalid before GetMessage() had a chance to process WM_QUIT (and return FALSE).

Also, the parameter to PostQuitMessage() is the wParam of the WM_QUIT message. PostQuitMessage() will always post a WM_QUIT, regardless of the parameter you give it.

This is the message loop I typically use:

Code:

---

int MessageLoop(HWND hwnd)
{
    MSG msg;
    BOOL bRet;
    while (1)
    {
        bRet = GetMessage(&msg, NULL, 0, 0);
        if ((bRet == 0) || (bRet == -1))
            break;

        if (!IsWindow(hwnd) || !IsDialogMessage(hwnd, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }//if
    }//while

    if (msg.message == WM_QUIT)
        return msg.wParam;
   
    return 0;
}//MessageLoop

---

gg

>> if (!IsWindow(hwnd) || !IsDialogMessage(hwnd, &msg))

You can take that out if you don't need "dialog box navigation" or WS_TABSTOP support. Then MessageLoop() wouldn't need the HWND parameter.

gg