C#

using System; 
using System.Net; 
using System.Net.Sockets; 
using System.IO; 
using System.Threading; 
using System.Collections; 
using System.Text; 

public class ClientHandler 
{ 
   public TcpClient clientSocket; 

   public void RunClient() 
   { 
      // Create the stream classes 
      StreamReader readerStream = new StreamReader(clientSocket.GetStream()); 
      NetworkStream writerStream = clientSocket.GetStream(); 

      string returnData = readerStream.ReadLine(); 
      string userName = returnData; 

      Console.WriteLine("Welcome " + userName + " to the Server"); 

      while (true) 
      { 
         returnData = readerStream.ReadLine(); 

         if (returnData.IndexOf("QUIT") > −1) 
         { 
            Console.WriteLine("Bye Bye " + userName); 
            break; 
         } 

         Console.WriteLine(userName + ": " + returnData); 
         returnData += "\r\n"; 

         byte[] dataWrite = Encoding.ASCII.GetBytes(returnData) 
         writerStream.Write(dataWrite,0,dataWrite.Length); 
      } 

      clientSocket.Close(); 
   } 
} 

public class EchoServer 
{ 
   const int ECHO_PORT = 8080; 

   public static void Main(string [] arg) 
   { 
      try 
      { 
         // Bind the server to the local port 
         TcpListener clientListener = new TcpListener(ECHO_PORT); 

         // Start to listen 
         clientListener.Start(); 

         Console.WriteLine("Waiting for connections…"); 

         while (true) 
         { 
            // Accept the connection 
            TcpClient client = clientListener.AcceptTcpClient(); 

            ClientHandler cHandler = new ClientHandler(); 

            // Pass value to the ClientHandler object 
            cHandler.clientSocket = client; 

            // Create a new thread for the client 
            Thread clientThread = new Thread(new ThreadStart(cHandler.RunClient)); 
            clientThread.Start(); 
         } 

         clientListener.Stop(); 
      } 
      catch(Exception exp) 
      { 
         Console.WriteLine("Exception: " + exp); 
      } 
   } 
} 

using System; 
using System.Net; 
using System.IO; 
using System.Net.Sockets; 
using System.Text; 

public class EchoClient 
{ 
   const int ECHO_PORT = 8080; 

   public static void Main(string [] arg) 
   { 
      Console.Write("Your UserName:"); 
      string userName = Console.ReadLine(); 
      Console.WriteLine("-----Logged In----->"); 

      try 
      { 
         // Create a connection with the ChatServer 
         TcpClient eClient = new TcpClient("127.0.0.1", ECHO_PORT); 

         // Create the stream classes 
         StreamReader readerStream = new StreamReader(eClient.GetStream()); 
         NetworkStream writerStream = eClient.GetStream(); 

         string dataToSend; 

         dataToSend = userName; 
         dataToSend += "\r\n"; 

         // Send username to the server 
         byte[] data = Encoding.ASCII.GetBytes(dataToSend); 

         writerStream.Write(data,0,data.Length); 

         while(true) 
         { 
            Console.Write(userName + ":"); 

            // Read line from server 
            dataToSend = Console.ReadLine(); 
            dataToSend += "\r\n"; 

            data = Encoding.ASCII.GetBytes(dataToSend); 
            writerStream.Write(data, 0, data.Length); 

            // If QUIT is sent, then quit application 
            if (dataToSend.IndexOf("QUIT") > −1) 
               break; 

            string returnData; 

            // Receive response from server 
            returnData = readerStream.ReadLine(); 

            Console.WriteLine("Server: " + returnData); 
         } 

         // Close TcpClient 
         eClient.Close(); 
      } 
      catch(Exception exp) 
      { 
         Console.WriteLine("Exception: " + exp); 
      } 
   } 
} 

void RunClient()
{
    // Create the stream classes
    StreamReader readerStream = new StreamReader(clientSocket.GetStream());
    NetworkStream writerStream = clientSocket.GetStream();

    string returnData = readerStream.ReadLine();
    string userName = returnData;

    // Add a user
    users.Add(userName, clientSocket);

    Console.WriteLine("Welcome " + userName + " to the Server");

    while (true)
    {
        returnData = readerStream.ReadLine();
        String tempData = returnData.ToLower();

        if (tempData.IndexOf("quit") > -1)
        {
            Console.WriteLine("Bye Bye " + userName);
            break;
        }

        Console.WriteLine(userName + ": " + returnData);
        returnData += "\r\n";

        byte[] dataWrite = Encoding.ASCII.GetBytes(returnData);

        TcpClient[] tcpClients = new TcpClient[users.Count];
        users.Values.CopyTo(tcpClients, 0);
        for (int i = 0; i < tcpClients.Length; i++)
        {
            NetworkStream tempWriteStream = tcpClients[i].GetStream();
            tempWriteStream.Write(dataWrite, 0, dataWrite.Length);
            tempWriteStream = null;
        }
    }

    clientSocket.Close();
}

string text = TextBox1.Text;

string[] split = text.split('@');

if(split.length == 1)//only one '@' character
{
   if(split[1].Contains('.'))
       //Could be a valid email
}
//else is not a valid email address

musefan wrote:

well one option would be to check for a '@' character in the textbox.Text string, then see if there is atleast one '.' character after the '@' character.

<asp:TextBox ID="tbEmail" runat="server" ValidationGroup="Register" />

<asp:RegularExpressionValidator ForeColor="Red" ValidationGroup="Register" ControlToValidate="tbEmail" ErrorMessage="Email Address is not valid." ValidationExpression="^([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$" EnableClientScript="true" ID="RegularExpressionValidator1" runat="server" Display="Dynamic" />

abu rakan wrote:

hi men

foreach (string color in Enum.GetNames(typeof(KnownColor)))
{
    // print the color name
    // use Color.FromName(...) to create an instance of the Color class
    // etc
}