Is there a difference if I added the window handle or NULL value
handle, null, winapi, windows
Solution
The problem you encounter in your second example is that after your window is destroyed, the window handle you supply to `GetMessage()` is no longer valid. Every subsequent call returns an error to notify you of that (with `GetLastError()` giving `ERROR_INVALID_WINDOW_HANDLE`), but the code doesn’t handle this case and so ends up in a busy loop forever.
This is why the MSDN Library page for `GetMessage()` advises against using `while (GetMessage(...))`.
Problem
I have a little problem. I will show you an example firstly, then I will tell you what the problem. Example: ``` while(GetMessage(&msg, NULL, 0, 0)){ TranslateMessage(&msg); DispatchMessage(&msg); } ``` That example work correctly, but if the parameter 2 in "GetMessage" function changed to a handle name of window as the following: Example2: after changed ``` while(GetMessage(&msg, Hwnd, 0, 0)){ TranslateMessage(&msg); DispatchMessage(&msg); } ``` Will occurs a little problem when exit the program. still the program works in processes list. And need to select it then click on end process button to terminate the program And now, Is there a difference between add (NULL or window handle)?