private static extern int SendMessage(
IntPtr hWnd, // 信息发往的窗口的句柄
int Msg, // 消息ID
int wParam, // 参数1
ref HdCAD_lParam lParam
);
public static void SendMsg(string lpWindowName, string msg)
{
IntPtr ptr = FindWindow(null, lpWindowName);//获取接收消息的窗体句柄
//消息构建
HdCAD_lParam m = new HdCAD_lParam();
m.s = msg;
m.i = m.s.Length;
SendMessage(ptr, HDCAD_MESSAGE, 1, ref m);//发送消息
}