C# 发送WM_COPYDATA消息

using  System.Runtime.InteropServices; 

[DllImport( " User32.dll " , EntryPoint  =   " FindWindow " )]
         private   static   extern  IntPtr FindWindow( string  lpClassName,
string  lpWindowName);
        [DllImport( " User32.dll " , EntryPoint  =   " SendMessage " )]    // 用于发送信息给窗体   
         private   static   extern   int  SendMessage(IntPtr hWnd,
int  Msg, IntPtr wParam,  ref  COPYDATASTRUCT lParam);
        [StructLayout(LayoutKind.Sequential)]

         public   struct  COPYDATASTRUCT
         {

            public IntPtr dwData;

            public int cbData;

            public IntPtr lpData;

        }

          COPYDATASTRUCT cds;
             string  a  =   " 032 " ;
             byte [] sarr  =  System.Text.Encoding.Default.GetBytes(a);

            cds.dwData  =  (IntPtr) 0 ;
            cds.cbData  =  a.Length;
            cds.lpData  =  Marshal.AllocHGlobal(sarr.Length);
            Marshal.Copy(sarr,  0 , cds.lpData, sarr.Length);

            IntPtr p  =  FindWindow( " #32770 " ,  " GetMessage " );
            SendMessage(p,  0x004A , (IntPtr) 0 , ref  cds);