【C#】Send data between applications

This sample shows how to send data between different applications, including object data——transform object into byte[] and then transport its CPU location.

Now I'll paste the programs here.(Thanks the blogger Sir.jevan for the template he/she provide,what I have done is just make the object-transportation available.Here is his page.)

Sender:

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows.Forms;
 using System.Runtime.InteropServices;
 using System.IO;  //The following four usings are important.So are they in Reciever and dll.
 using System.Runtime.Serialization.Formatters.Binary;
 using System.Runtime.Serialization;
 using ClassLibrary1;

 namespace cdn_send
 {
     public partial class Form1 : Form
     {
         public Form1()
         {
             InitializeComponent();
         }        

         private void Form1_Load(object sender, EventArgs e)
         {
         }

         private const int WM_COPYDATA = 0x004A;
         private const uint flag = 0x8000; //I can't understand it.Please tell me(if you got it).
         [DllImport("User32.dll", EntryPoint = "SendMessage")]
         private static extern int SendMessage(int hWnd, int Msg, int wParam, ref COPYDATASTRUCT lParam);
         [DllImport("User32.dll", EntryPoint = "FindWindow")]
         private static extern int FindWindow(string lpClassName, string lpWindowName);
         [DllImport("kernel32.dll")]
         static extern uint GetTickCount();

         private void button1_Click(object sender, EventArgs e)
         {
             int WINDOW_HANDLER = FindWindow(null, @"xxx");  //Find target window.Well,by the way,it's called 'xxx'.
             if (WINDOW_HANDLER == )
             {
                 MessageBox.Show("xxx");
             }
             else
             {

                 data dd=new data();  //Process data.
                 dd.x = (int)this.Handle;
                 dd.y = DateTime.Now;
                 dd.tx = textBox1.Text;
                 dd.tk = GetTickCount();
                 byte[] bt=(new switcher()).Object2Bytes((object)dd);  //Type switch.

                 COPYDATASTRUCT cds;
                 cds.dwData = (IntPtr)flag;
                 cds.cbData = bt.Length;
                 cds.lpData = Marshal.AllocHGlobal(bt.Length);  //Allocate space.

                 Marshal.Copy(bt, , cds.lpData, bt.Length);  //Memory copy.
                 SendMessage(WINDOW_HANDLER, WM_COPYDATA, , ref cds);  //Send message out.
             }
         }
     }

 }

Reciever:

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows.Forms;
 using System.Runtime.InteropServices;
 using System.IO;  //Important.
 using System.Runtime.Serialization.Formatters.Binary;
 using System.Runtime.Serialization;
 using ClassLibrary1;

 namespace cdn_receiver
 {
     public partial class Form1 : Form
     {

         public Form1()
         {
             InitializeComponent();
         }
         private void Form1_Load(object sender, EventArgs e)
         {

         }

         const int WM_COPYDATA = 0x004A;
         private const uint flag = 0x8000;
         [DllImport("kernel32.dll")]
         public static extern uint GetTickCount();

         protected override void DefWndProc(ref System.Windows.Forms.Message m)
         {
             switch (m.Msg)
             {
                 case WM_COPYDATA:

                     COPYDATASTRUCT cds = new COPYDATASTRUCT();
                     cds = (COPYDATASTRUCT)m.GetLParam(cds.GetType()); //Receive information.

                     byte[] bt = new byte[cds.cbData];
                     Marshal.Copy(cds.lpData,bt,,bt.Length);  //Get data array.

                     data dd = (data)((new switcher()).Bytes2Object(bt));  //Transform back.
                     long xx = GetTickCount() - dd.tk;  //This line is used to calculate its delay,although mostly it is 0ms.
                     textBox1.Text = (dd.x.ToString() + " " + dd.y.ToString() + " " + dd.tx);
                     textBox1.Text += "\r\n" + xx.ToString() + "ms";

                     break;
                 default:
                     base.DefWndProc(ref m);  //Don't forget this line,or it cannot run properly.
                     break;
             }

         }
     }

 }

Dll:

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Runtime.InteropServices;
 using System.Runtime;
 using System.IO; //Important
 using System.Runtime.Serialization;
 using System.Runtime.Serialization.Formatters.Binary;
 namespace ClassLibrary1
 {

     [Serializable]  //My datastructure which contains different types.Don't forget this line.
     public struct data
     {
         public int x;
         public DateTime y;
         public string tx;
         public long tk;
     }

     [StructLayout(LayoutKind.Sequential)]  //The datastructure which used as a media to transport.
     public struct COPYDATASTRUCT
     {
         public IntPtr dwData;
         public int cbData;
         public IntPtr lpData;
     }

     public class switcher  //The switcher object which contains two main switcher function.
     {
         public byte[] Object2Bytes(object obj)
         {
             IFormatter fmt = new BinaryFormatter();
             MemoryStream ms = new MemoryStream();
             fmt.Serialize(ms, obj);
             return ms.GetBuffer();

         }

         public object Bytes2Object(byte[] bt)
         {
             IFormatter fmt = new BinaryFormatter();
             MemoryStream ms = new MemoryStream(bt);
             return (object)fmt.Deserialize(ms);
         }

         public switcher(){
         }
     }

 }

It is tested that there is no problem with the correction of the transported data.(My vs version is 2012 ultimate,OS version is win7)