CreateWindowEx and last parameter..

Can someone explain the use of the last parameter in the CreateWindowEx, called void* pParam or something like that?
I believe it is used to pass a pointer to be used with the WndProcedure, but im not sure. And if thats the case, I really need it.. But how do we use it?

Check the docs: CreateWindow()

gg

Very.. informative.. I've been there many times, thanks. Anything else?

Quote:

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Originally Posted by aker_y3k

Can someone explain the use of the last parameter in the CreateWindowEx, called void* pParam or something like that?
I believe it is used to pass a pointer to be used with the WndProcedure, but im not sure. And if thats the case, I really need it.. But how do we use it?

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Quote:

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Originally Posted by Codeplug

Check the docs: CreateWindow()

gg

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Quote:

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Originally Posted by msdn, CreateWindow, last parameter

pParam
[in] Pointer to a value to be passed to the window through the CREATESTRUCT structure passed in the lpParam parameter the WM_CREATE message. If an application calls CreateWindow to create a multiple-document interface (MDI) client window, lpParam must point to a CLIENTCREATESTRUCT structure.

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Quote:

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Originally Posted by msdn,CREATESTRUCT,lpCreateParam

Contains additional data which may be used to create the window. If the window is being created as a result of a call to the CreateWindow or CreateWindowEx function, this member contains the value of the lpParam parameter specified in the function call.

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Quote:

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Originally Posted by aker_y3k

Very.. informative

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Indeed it is. :)

Here's a quick example of how to use the last parameter,

Code:

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#include <windows.h>

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_CREATE:
                {
                        CREATESTRUCT *cs = (CREATESTRUCT*)lParam;
                        MessageBox(0,(char*)cs->lpCreateParams,"",0);
                        delete[] cs->lpCreateParams;
                        return 0;
                }
        case WM_CLOSE:
                DestroyWindow(hwnd); break;
        case WM_DESTROY:
                PostQuitMessage(0);  break;
        default:
            return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;

    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style        = 0;
    wc.lpfnWndProc  = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance    = hInstance;
    wc.hIcon        = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor      = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = "WindowCls";
    wc.hIconSm      = LoadIcon(NULL, IDI_APPLICATION);

    if(!RegisterClassEx(&wc))
        return 0;

        char * passValue = new char[10];
        strcpy(passValue,"hello...");

    hwnd = CreateWindowEx(WS_EX_CLIENTEDGE, "WindowCls", "Window", WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 100, 100, NULL, NULL, hInstance, passValue);

    if(hwnd == NULL)
        return 0;

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

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

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Seriously though, the information was right there, all you had to do was read it.

-r1ck0r

Ah, thanks.
I read it, but didn't understand it.