How Can I Close exe files with C++ code ?

[JohnW@Wessex]

Open

    ::ShellExecute(NULL,
                   "open",
                   "Calc.exe",
                   "",
                   "",
                   SW_SHOWNORMAL);

Close

    CWnd *window = CWnd::FindWindow(NULL,     LPCTSTR("Calculator"));

    if (window != NULL)
    {
        window->PostMessage(WM_CLOSE);
    }