How to turn off your monitor

namespace TurnoffMonitor
{
    /// 

    /// Interaction logic for MainWindow.xaml
    /// 
    public partial class MainWindow : Window
    {
        [DllImport("user32.dll")]
        static extern IntPtr SendMessage(IntPtr hWnd, uint Msg,
                      IntPtr wParam, IntPtr lParam);

        const int SC_MONITORPOWER = 0xF170;
        const uint WM_SYSCOMMAND = 0x0112;
        
        const int MONITOR_ON = -1;
        const int MONITOR_OFF = 2;
        const int MONITOR_STANBY = 1;
        
        public MainWindow()
        {
            InitializeComponent();
        }

        private void ExecuteButton_Click(object sender, RoutedEventArgs e)
        {
            WindowInteropHelper helper = new WindowInteropHelper(this);
            var handle = helper.Handle;

            
            SendMessage(handle, WM_SYSCOMMAND, new IntPtr(SC_MONITORPOWER), new IntPtr(MONITOR_OFF));
        }
    }
}