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);