Efficiency coding; a simple top-level window

I'd like to know how other programmers go about creating a simple window in Win32. If there's anything in my code that could be made more efficient, or which has been superseded, I'd love to know, thanks.

Code:

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#include <windows.h>

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow);
LRESULT CALLBACK WndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam);

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow)
{
        WNDCLASSEX wcx;
       
        wcx.cbClsExtra=0;
        wcx.cbSize=sizeof(WNDCLASSEX);
        wcx.cbWndExtra=0;
        wcx.hbrBackground=(HBRUSH)(COLOR_BTNFACE+1);
        wcx.hCursor=LoadCursor(NULL,IDC_ARROW);
        wcx.hIcon=LoadIcon(NULL,IDI_APPLICATION);
        wcx.hIconSm=NULL;
        wcx.hInstance=hInstance;
        wcx.lpfnWndProc=WndProc;
        wcx.lpszClassName="clsAccess";
        wcx.lpszMenuName=NULL;
        wcx.style=0;

        if (!RegisterClassEx(&wcx))
                exit(1);

        HWND hwnd;

        hwnd=CreateWindow("clsAccess","Access Manager",
                                WS_OVERLAPPEDWINDOW,
                                0,0,0,0,NULL,NULL,hInstance,NULL);

        if (!hwnd)
                exit(2);

        ShowWindow(hwnd,SW_SHOW);
        UpdateWindow(hwnd);

        MSG msg;

        while (GetMessage(&msg,hwnd,0,0)>0)
        {
                TranslateMessage(&msg);
                DispatchMessage(&msg);
        }

        return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam)
{
        switch (msg)
        {
        case WM_DESTROY:
                PostQuitMessage(0);
                return 0;

        case WM_CREATE:
                SetWindowPos(hwnd,NULL,
                        GetSystemMetrics(SM_CXSCREEN)/4,
                        GetSystemMetrics(SM_CYSCREEN)/4,
                        GetSystemMetrics(SM_CXSCREEN)/2,
                        GetSystemMetrics(SM_CYSCREEN)/2,
                        SWP_NOOWNERZORDER);
                break;

        default:
                break;
        }

        return DefWindowProc(hwnd,msg,wParam,lParam);
}

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More efficient? If your finding that slow then I guess it's more to do with the os than your code

Though as you seem to be in C++ (with variables declared throughout the block and not at the top), why not

WNDCLASSEX wcx = {0};

Then you dont need to keep assigning NULL or zero to the relevant members of that struct.

Also, why bother calling exit() when you can use a simple return with that value you want and allow the compiler generated code to destroy the process.

None of these are real efficiency tips...you would never in a million years notice a benefit from my suggestions

It's not for speed, it's just general things that I should be doing. Looks like it's okay though. Thanks.

Quote:

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Warning

Because the return value can be nonzero, zero, or -1, avoid code like this:

Code:

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while (GetMessage( lpMsg, hWnd, 0, 0))
...

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The possibility of a -1 return value means that such code can lead to fatal application errors. Instead, use code like this:

Code:

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BOOL bRet;

while( (bRet = GetMessage( &msg, NULL, 0, 0 )) != 0)
{
    if (bRet == -1)
    {
        // handle the error and possibly exit
    }
    else
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
}

---

---

Eibro, thanks for the tip. Now here's a tip for you: go back and read my code.

Hahahaha! :p

But the documentation for GetMessage() says that sucess could be anything non-zero or -1. So -5 could be success. I'd recommend using Eibro's code anyways.

Quote:

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Originally posted by bennyandthejets
Eibro, thanks for the tip. Now here's a tip for you: go back and read my code.

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Again, here's a tip for you: Do what I suggested. That was quoted straight from MSDN.

I was indignant until I read Speedy5's addition to his/her original post. I had forgotten that non-zero included negatives too. Sorry Eibro. I haven't run into any problems in the past with that one. Has anyone?

EDIT: Being a follower of the Church of MSDN doesn't make everything you say correct. Speedy5's explanation had substance to it.