Do you have to register a Dialog Box?

Question

So, I am a total beginner in any kind of Windows related programming. I have been playing around with the Windows API and came across a couple of examples on how to initialize create windows and such.

One example creates a regular window (I abbreviated some of the code):

int WINAPI WinMain( [...] )
{

    [...]

    // Windows Class setup
    wndClass.cbSize = sizeof( wndClass );
    wndClass.style  = CS_HREDRAW | CS_VREDRAW;
    [...]    

    // Register class
    RegisterClassEx( &wndClass );

    // Create window
    hWnd = CreateWindow( szAppName, "Win32 App",
                         WS_OVERLAPPEDWINDOW,
                         0, 0, 512, 384,
                         NULL, NULL, hInstance, NULL );
    [...]
}

The second example creates a dialog box (no abbreviations except the WinMain arguments):

int WINAPI WinMain( [...] )
{
    // Create dialog box
    DialogBox(hInstance, 
              MAKEINTRESOURCE(IDD_MAIN_DLG), 
              NULL, 
              (DLGPROC)DialogProc);
}

The second example does not contain any call to the register function. It just creates the DialogBox with its DialogProc process attached.

This works fine, but I am wondering if there is a benefit of registering the window class and then creating the dialog box (if this is at all possible).

Answer 1

You do not have to register a dialog box.

Dialog boxes are predefined so (as you noted) there is no reference to a window class when you create a dialog. If you want more control of a dialog (like you get when you create your own window class) you would subclass the dialog which is a method by which you replace the dialogs window procedure with your own. When your procedure is called you modify the behavior of the dialog window; you then might or might not call the original window procedure depending upon what you're trying to do.

Answer 2

It's been a while since I've done this, but IIRC, the first case is for creating a dialog dynamically, from an in-memory template. The second example is for the far more common case of creating a dialog using a resource. The dynamic dialog stuff in Win32 was fairly complex, but it allowed you to create a true data-driven interface, and avoid issues with bundling resources with DLLs.

As for why use Win32 - if you need a windows app and you don't want to depend on MFC or the .NET runtime, then that's what you use.

Answer 3

This is only tangentially related to the question, but if you are new to Windows programming, why are you using Win32? Unless there's a lot of low-end code (which should be separate to the GUI anyway), it probably makes more sense to use .NET, which should cause far less head injury as well.