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using System.Net.Sockets;
using System.Net;
using System.Threading;

namespace ChatUDPVersion
{
    public partial class frmChat : Form
    {
        delegate void SetTextCallback(string text);

        bool isOpen = true;
        Thread thread;

        public frmChat()
        {
            InitializeComponent();
        }

        private void btnSend_Click(object sender, EventArgs e)
        {         
            UdpClient clientSend = new UdpClient(Dns.GetHostName(), 8008);
            try
            {
                Byte[] sendInfo = Encoding.Default.GetBytes(tbSend.Text);
                clientSend.Send(sendInfo, sendInfo.Length);
                tbSend.Text = string.Empty;
            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
                clientSend.Close();
            }
        }
        private void GetMessage()
        {
            UdpClient client = new UdpClient(8008);
            IPEndPoint ipRemoteEndPoint = new IPEndPoint(IPAddress.Any, 8008);
            byte[] receInfo;
            while (isOpen)
            {
                try
                {
                    receInfo = client.Receive(ref ipRemoteEndPoint);
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                    break;
                }
                AddMessage(Encoding.Default.GetString(receInfo));
            }
            client.Close();
        }

        public void AddMessage(string message)
        {
            if (this.lbReceive.InvokeRequired)
            {
                SetTextCallback d = new SetTextCallback(AddMessage);
                this.Invoke(d, new object[] { message });
            }
            else
            {
                lbReceive.Items.Add(message);
            }
        }

        private void frmChat_Load(object sender, EventArgs e)
        {
          
            thread = new Thread(new ThreadStart(this.GetMessage));
            thread.IsBackground = true;
            thread.Start();  
        }

        private void frmChat_FormClosing(object sender, FormClosingEventArgs e)
        {
            isOpen = false;
            Application.Exit();
        }
    }
}