multi client to server in C#

[moii]

this is the client code ! You can try it .

[moii]

namespace Client
{
	public partial class ClientForm : Form
	{
		const int BUFFER_SIZE = 1024;
		byte[] sendBuffer = new byte[BUFFER_SIZE];

		byte[] rcvBuffer = new byte[BUFFER_SIZE];
		Socket clientSocket;
		const int PORT = 3333;

		public ClientForm()
		{
			InitializeComponent();
		}

		void btnConnect_Click(object sender, EventArgs e)
		{
			string serverIP = "192.168.1.200";
			try
			{
				this.clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
				// Connect to the local host
				clientSocket.Connect(new IPEndPoint(IPAddress.Parse(serverIP), PORT));
				// Prepares to receive something, i.e. the echo
				clientSocket.BeginReceive(rcvBuffer, 0, rcvBuffer.Length, SocketFlags.None, ReceiveCallback, null);
				EnableSendButton();
			}
			catch (Exception ex) { AppendToTextBox(ex.Message); }
		}

		void btnSend_Click(object sender, EventArgs e)
		{
			try
			{
				// Serialize the textBox text before sending
				sendBuffer = Encoding.ASCII.GetBytes(textBoxInput.Text);

				// Sends contents of textbox to the server
				clientSocket.Send(sendBuffer);

				// Prepares to receive something, i.e. the echo
				clientSocket.BeginReceive(rcvBuffer, 0, rcvBuffer.Length, SocketFlags.None, ReceiveCallback, null);//.Receive(rcvBuffer);
			}
			catch (Exception ex) { AppendToTextBox(ex.Message); }
		}

		// About Asynchronous Callbacks: [url]http://stackoverflow.com/questions/1047662/what-is-asynccallback[/url]
		void ReceiveCallback(IAsyncResult AR)
		{
			try
			{
				int bytesReceived = clientSocket.EndReceive(AR);	// Number of bytes received
				if (bytesReceived == 0) return;
				byte[] rcvBufferTrim = new byte[bytesReceived];
				Array.Copy(rcvBuffer, rcvBufferTrim, bytesReceived);	// Removes trailing nulls
				string text = Encoding.ASCII.GetString(rcvBufferTrim);	// Convert bytes into string
				AppendToTextBox(DateTime.Now.ToString("HH:mm:ss") + ": " + text);		// Displays buffer contents as text

				// Starts receiving data again
				clientSocket.BeginReceive(rcvBuffer, 0, rcvBuffer.Length, SocketFlags.None, ReceiveCallback, null);
			}
			catch (Exception ex) { AppendToTextBox(ex.Message); }
		}

		// Provides a thread-safe way to enable the send button/disable the connect button
		void EnableSendButton()
		{
			MethodInvoker invoker = new MethodInvoker(delegate
			{
				btnSend.Enabled = true;
				btnConnect.Enabled = false;
				btnDisconnect.Enabled = true;
				textBoxInput.ReadOnly = false;
				btnDisconnect.Enabled = true;
			});
			this.Invoke(invoker);
		}

		private void textBoxInput_KeyDown(object sender, KeyEventArgs e)
		{
			if (btnSend.Enabled == true
				&& Control.ModifierKeys != Keys.Shift
				&& e.KeyCode == Keys.Return)
			{
				MethodInvoker invoker = new MethodInvoker(delegate { btnSend.PerformClick(); });
				this.Invoke(invoker);
				e.SuppressKeyPress = true;
			}
		}

		// Provides a thread-safe way to append text to the textbox
		void AppendToTextBox(string text)
		{
			MethodInvoker invoker = new MethodInvoker(delegate
			{
				textBoxDisplay.Text += text + "\r\n";
				textBoxDisplay.SelectionStart = textBoxDisplay.TextLength;
				textBoxDisplay.ScrollToCaret();
			});	// "\r\n" are for new lines
			try { this.Invoke(invoker); }
			catch { };
		}

		private void btnDisconnect_Click(object sender, EventArgs e)
		{
			sendBuffer = Encoding.ASCII.GetBytes("disconnect");
			clientSocket.Send(sendBuffer);

			clientSocket.Shutdown(SocketShutdown.Both);
			clientSocket.Close();

			this.Close(); // Close the window
		}

        private void textBoxDisplay_TextChanged(object sender, EventArgs e)
        {

        }
	}
}

[moii]

Don't forget this for client :

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;
using System.Net.Sockets;