You can use the DestroyWindow function to destroy a window. Typically, an application sends the WM_CLOSE message before destroying a window, giving the window the opportunity to prompt the user for confirmation before the window is destroyed. A window that includes a window menu automatically receives the WM_CLOSE message when the user chooses the Close command from the menu. If the user confirms that the window should be destroyed, the application calls DestroyWindow. Windows sends the WM_DESTROY message to the window after removing it from the screen. In response to WM_DESTROY, the window saves its data and frees any resources it allocated. A main window concludes its processing of WM_DESTROY by calling the PostQuitMessage function to quit the application.
The following example shows how to prompt for user confirmation before destroying a window. In response to WM_CLOSE, the example displays a dialog box that contains Yes, OK, and Cancel buttons. If the user clicks the Yes button, DestroyWindow is called; otherwise, the window is not destroyed. Because the window being destroyed is a main window, the example calls PostQuitMessage in response to WM_DESTROY.
case WM_CLOSE:
// Create the message box. If the user clicks
// the Yes button, destroy the main window.
if (MessageBox(hwnd, szConfirm, szAppName,
MB_YESNOCANCEL) == IDYES)
DestroyWindow(hwndMain);
else
return 0;
case WM_DESTROY:
// Post the WM_QUIT message to
// quit the application terminate.
PostQuitMessage(0);
return 0;