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Invalid conversion from void problem

Hashimatsu (179)
I'm following a tutorial on making windows GUI using Win32 API. I've done this according to the tutorial:

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#include <windows.h>

#define ID_FILE_EXIT 9001
#define ID_STUFF_GO 9002

const char g_szClassName[] = "myWindowClass";

// Step 4: the Window Procedure
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_CREATE:
        {
            HMENU hMenu, hSubMenu;
            HICON hIcon, hIconSm;

            hMenu = CreateMenu();

            hSubMenu = CreatePopupMenu();
            AppendMenu(hSubMenu, MF_STRING, ID_FILE_EXIT, "E&xit");
            AppendMenu(hMenu, MF_STRING | MF_POPUP, (UINT)hSubMenu, "&File");

            hSubMenu = CreatePopupMenu();
            AppendMenu(hSubMenu, MF_STRING, ID_STUFF_GO, "&Go");
            AppendMenu(hMenu, MF_STRING | MF_POPUP, (UINT)hSubMenu, "&Stuff");

            SetMenu(hwnd, hMenu);


            hIcon = LoadImage(NULL, "menu_two.ico", IMAGE_ICON, 32, 32, LR_LOADFROMFILE);
            if(hIcon)
                SendMessage(hwnd, WM_SETICON, ICON_BIG, (LPARAM)hIcon);
            else
                MessageBox(hwnd, "Could not load large icon!", "Error", MB_OK | MB_ICONERROR);

            hIconSm = LoadImage(NULL, "menu_two.ico", IMAGE_ICON, 16, 16, LR_LOADFROMFILE);
            if(hIconSm)
                SendMessage(hwnd, WM_SETICON, ICON_SMALL, (LPARAM)hIconSm);
            else
                MessageBox(hwnd, "Could not load small icon!", "Error", MB_OK | MB_ICONERROR);
        }
        break;
        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;

    //Step 1: Registering the Window Class
    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)(COLOR_WINDOW+1);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = g_szClassName;
    wc.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);

    if(!RegisterClassEx(&wc))
    {
        MessageBox(NULL, "Window Registration Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    // Step 2: Creating the Window
    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        g_szClassName,
        "The title of my window",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 240, 120,
        NULL, NULL, hInstance, NULL);

    if(hwnd == NULL)
    {
        MessageBox(NULL, "Window Creation Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

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

    // Step 3: The Message Loop
    while(GetMessage(&Msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }
    return Msg.wParam;
}


And I get following error:

Line 31 error: invalid conversion from 'void*' to 'HICON__*'
Line 37 error: invalid conversion from 'void*' to 'HICON__*'


I use Code::Blocks and GNU GCC Compiler.

Any help will be much appreciated.

Thanks in advance
Aceix (1118)
Yeah you must explicitly type-cast the return value into an HICON value.
eg: hIcon = (HICON) LoadImage(NULL, "menu_two.ico", IMAGE_ICON, 32, 32, LR_LOADFROMFILE);

But I wander why you load an icon in the window message WM_CREATE, and not in the class
Last edited on
Hashimatsu (179)
Completely forgot about the (HICON) even tho I've read about it yesterday. Feeling stupid. =)

I'm loading images in WM_CREATE cause it's how it's done in the tutorial. Don't know how else to do this except creating an resource.rc and *.h file and include them.

Which one's the better, I don't know
Aceix (1118)
Yeah, the resource file, I also use it but I was saying you could have made that window class have a default icon by specifying it in the hIcon and hIconSm members of the WNDCLASSEX structure.
Last edited on
Hashimatsu (179)
I did in the first part of the tutorial, but then "we look at another example" and ta-da! We made it more complicated than it has to be. Really great... =)

Thanks for pointing it out
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