UDP写的点对点的聊天程序，需要写IP

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Code

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Net.Sockets;

using System.Net;

using System.Threading;

namespace point_talk_to_face

{

    public partial class Form1 : Form

    {

      

        public Form1()

        {

            InitializeComponent();

        }

        private Thread th;

        UdpClient udp, udp2;

        bool l = true;

        private void textBox2_TextChanged(object sender, EventArgs e)

        {

        }

        private void Form1_Load(object sender, EventArgs e)

        {

           System.Windows.Forms.Control.CheckForIllegalCrossThreadCalls = false; 

           th = new Thread(new ThreadStart(Listen));

           th.Start();

        }

        private void button1_Click(object sender, EventArgs e)

        {

   /*****************************SEND****************************************************/

                udp2 = new UdpClient(textBox3.Text,9999);

                Byte[] data = Encoding.ASCII.GetBytes(textBox2.Text);

                udp2.Send(data, data.Length);

                textBox1.AppendText("我对"+textBox3.Text+"说："+textBox2.Text+"\n");

                udp2.Close();

               this.textBox2.Clear();

                textBox2.Focus();

   /**********************************SEND*****************************************************/

        }

        private void Listen()

        {

  /********************************************RECEIVE**************************************************/

            udp = new UdpClient(9999);

            IPEndPoint remoteiep = new IPEndPoint(IPAddress.Any, 9999);

            while (l)

            {

                try

                {

                    Byte[] data = udp.Receive(ref remoteiep);

                    if (data.Length > 0)

                    {

                        string word = Encoding.ASCII.GetString(data);

                        label1.Text = remoteiep.Address.ToString();

                        label2.Text = remoteiep.Port.ToString();

                        textBox1.AppendText(label1.Text + "对我说：" + word.ToString() + "\n");

                    }

                    else

                    {

                        

                    }

                }

                catch (Exception ex)

                {

            //        textBox1.AppendText(ex.Message);

            //          MessageBox.Show(ex.Message.ToString());

                }

            }

    /*******************************************RECEIVE***********************************************************/

        }

        private void textBox1_TextChanged(object sender, EventArgs e)

        {

        }

        private void close(object sender, FormClosingEventArgs e)

        {  

            th.Abort();

            l = false;

            udp.Close();

        }

        private void Form1_FormClosed(object sender, FormClosedEventArgs e)

        {

        }

    }

}