How to make a simple Win32 program

[FearOfTheDark^]

After i started programming in unmanaged C++ i have realized how incredibly much the .NET framework has done to make programming simple. Im now going to show you how to make a window in a Win32 program.
This tutorial assumes that you have a basic knowledge of C++.

Lets start with the headers. You need to include <Windows.h> for the window functions, and thats about it. Then, you need your windows main function and your window procedure. I will take you step by step through them.

int       WINAPI   WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int iCmdShow);
LRESULT   CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

Okay thats the easy part. Now for the hard part.

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int iCmdShow) {
    WNDCLASS wc;     
    MSG msg;
    BOOL Quit = false;
    HWND hWnd = NULL;

We will need these two variables to store our window class, for retrieving messages and to decide when to quit.

Next comes the code that sets the info about our window. It sets information such as background color, the window procedure, the icon, the cursor, a menu, and most important; the class name.

    wc.style = CS_OWNDC;
    wc.lpfnWndProc = WndProc; //Window procedure
    wc.cbClsExtra = 0; //Extra space (in bytes) for the application
    wc.cbWndExtra = 0; //Extra space (in bytes) for each window
    wc.hInstance = hInstance; //Instance
    wc.hIcon = LoadIcon (NULL, IDI_APPLICATION); //Icon
    wc.hCursor = LoadCursor (NULL, IDC_ARROW); //Cursor
    wc.hbrBackground = CreateSolidBrush(RGB(123, 123, 123)); //Background
    wc.lpszMenuName = NULL; //No menu
    wc.lpszClassName = "MyWindow"; //Class name

Then we have to register the class

    RegisterClass (&wc);

Now we have come far enough to create our window, it has been much more work than Dim form = New Form1 hasn't it?

    hWnd = CreateWindow (
      "MyWindow", "Awesome Window Title",  //MyWindow MUST be the same as the lpszClassName ^^
      WS_OVERLAPPEDWINDOW, //Window style
      0, 0, 600, 300, //x, y, width, height
      NULL, NULL, hInstance, NULL); //parent, menu, app instance, ?? lpvoid ??

So we have to show our window:

    ShowWindow(hWnd, 5);

Now comes our message loop, this catches care of all incoming messages and processes them.

    while (!Quit)
    {
        if (PeekMessage (&msg, NULL, 0, 0, PM_REMOVE))
        {
            if (msg.message == WM_QUIT)
            {
                Quit = TRUE;
            }
            else
            {
                TranslateMessage (&msg);
                DispatchMessage (&msg); //An indirect call to the WndProc you defined in wc.lpfnWndProc 
            }
        }
        else
        {
            //Application idle
        }         
    }

When your application is idle, it means that it has no messages to process, so it is free to do any task.
There is another way of coding the message loop too, that method waits until it gets a message to process, so your application is never idle (as far as i know). Feel free to use the one you like.

    while(!Quit) {
        while(GetMessage(&msg, NULL, 0, 0) > 0)
        {
            if (msg.message == WM_QUIT) { Quit = TRUE; }
            TranslateMessage(&msg);
            DispatchMessage(&msg); //Indirect call to wc.lpfnWndProc
        }
    }

Finally, we return the result returned from WndProc (wc.lpfnWndProc). 0 for success, and nonzero for fail.

    return msg.wParam;
}

Finally finished you might think, but no. This was just our main window function. Now we need to create our WndProc function. This handles messages for us.

LRESULT CALLBACK WndProc (HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {

hWnd is the window handle.
uMsg is the message id/type.
wParam and lParam is additional information for a message.
We have a switch statement to use the right code on the right message. In this tutorial we will handle WM_CREATE (creation) and WM_CLOSE (closing). We will leave the rest to DefWindowProc.

        case WM_CREATE:
             MessageBox(hWnd, "An awesome messagebox", "Title", MB_OK);
             return 0;
        
        case WM_CLOSE:
             MessageBox(hWnd, "Closing :(", ":'(", MB_OK);
             PostQuitMessage(0);
             return 0;
        
        default:
             return DefWindowProc(hWnd, uMsg, wParam, lParam);
    }
}

Now, finally we come to an end. If you managed to understand all this, I'm impressed. If everything was copy/paste, try again
Please leave a replay.

[just.punish]

nc post usefull

[VampAurora]

Thanks for sharing :P

[nilos]

Thats not C++, its C.
And there is also an autogenerated Win32 Window App in Visual Studio, similar to this.
Open Visual studio, go to File > New > Proect... > Visual C++ > Win32 Application