Thread: DialogBox Argument Invalid?

Hi, i searched around for all the dialog box problems on forum, and none seem to help me.

The error i get is this:
argument of type `BOOL (CppWnd:(HWND__*, UINT, WPARAM, LPARAM)' does not match `BOOL (*)(HWND__*, UINT, WPARAM, LPARAM)'

I'm sure that my program being in a really big Class, there are some variable losses or something going on. Heres the code:

In my OnCommand Function, which is called from the Case WM_COMMAND, i have this incase someone presses "about"

Code:

if((nID == IDD_ABOUTBOX) && (uNotifyCode == BN_CLICKED)){
       DialogBox(GetModuleHandle(NULL), MAKEINTRESOURCE(IDD_ABOUTBOX), hAppWnd, (DLGPROC)AboutDlgProc);
     }

hAppWnd is my HWND... IDD_ABOUTBOX HAS been defined.

I've declared the prototype in my header file too. Same way. My AboutDlgProc function is CppWnd::AboutDlgProc, and is BOOL CALLBACK.

However, i keep getting this error, i've tried every possible thing, but it doesnt work.

I think perhaps, the UINT Message, wParam and lParam are getting lost because I dont have DialogBox() inside the WndProc function under WM_COMMAND. But i am not sure.

ABOUT CODE:

Code:

BOOL CALLBACK CppWnd::AboutDlgProc(HWND hAppWnd, UINT Message, WPARAM wParam, LPARAM lParam)
{
    switch(Message)
    {
        case WM_INITDIALOG:

        return TRUE;
        case WM_COMMAND:
            switch(LOWORD(wParam))
            {
                case IDOK:
                    EndDialog(hAppWnd, IDOK);
                break;
                case IDCANCEL:
                    EndDialog(hAppWnd, IDCANCEL);
                break;
            }
        break;
        default:
            return FALSE;
    }
    return TRUE;
}

You can't use a normal class member function as a window procedure because it's of the wrong type (not a window or dialog procedure) - make it a static class member function instead.

Also, the return type for DialogProc is INT_PTR now.

Welcome to the boards.

Thx.

Ok, i used static, and it worked.

I also changed any mention of "BOOL" to INT_PTR.

EDIT: ok works ^^.
There was a small linker error, cuz i accidently removed CppWnd:: from in front of where AboutProc was defined.
There was an error also where i entered wrong ID for the Resource, so it wasnt loading.

Thanks for your help :O

im surprised you aren't having troubles with the procedure.

Usualy when you wrap procedures in classes you have to have 2... one statical and one non-statical

Code:

static LRESULT CALLBACK StaticWndProc(HWND hwnd, UINT msg,
								WPARAM wParam, LPARAM lParam)
	{
		if ( msg == WM_CREATE )
		{
			SetWindowLongPtr( hwnd, GWLP_USERDATA, (LONG)(LONG_PTR)((CREATESTRUCT *)lParam)->lpCreateParams );
		}
		
		CppApplication *targetApp = (CppApplication*)(LONG_PTR)GetWindowLongPtr( hwnd, GWLP_USERDATA );

		if ( targetApp )
		{
			return targetApp->WndProc( hwnd, msg, wParam, lParam );
		}

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

this what the statical procedure looks. When you create the window/dialog you have to pass a pointer of your class as the LPARAM.

On the WM_CREATE Message you can set the pointer as the window long pointer and then retrieve it everytime you get a new message.

Works pretty well, I hope this helps.