C#关闭显示屏，使显示屏处于待机状态

 class Program
 {
 private const uint WM_SYSCOMMAND = 0x112; //系统消息
 private const int SC_MONITORPOWER = 0xF170; //关闭显示器的系统命令
 private const int MonitorPowerOff = ; //2为PowerOff, 1为省电状态，-1为开机
 private static readonly IntPtr HWND_BROADCAST = new IntPtr(0xffff);//广播消息，所有顶级窗体都会接收

 [DllImport("user32.dll")]
 private static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);
 static void Main(string[] args)
 {
 SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, MonitorPowerOff);
 }

 }