static void Connect(String server, String message) 
{
  try 
  {
    // Create a TcpClient.
    // Note, for this client to work you need to have a TcpServer 
    // connected to the same address as specified by the server, port
    // combination.
    Int32 port = 13000;
    TcpClient client = new TcpClient(server, port);
    
    // Translate the passed message into ASCII and store it as a Byte array.
    Byte[] data = System.Text.Encoding.ASCII.GetBytes(message);         

    // Get a client stream for reading and writing.
   //  Stream stream = client.GetStream();
    
    NetworkStream stream = client.GetStream();

    // Send the message to the connected TcpServer. 
    stream.Write(data, 0, data.Length);

    Console.WriteLine("Sent: {0}", message);         

    // Receive the TcpServer.response.
    
    // Buffer to store the response bytes.
    data = new Byte[256];

    // String to store the response ASCII representation.
    String responseData = String.Empty;

    // Read the first batch of the TcpServer response bytes.
    Int32 bytes = stream.Read(data, 0, data.Length);
    responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);
    Console.WriteLine("Received: {0}", responseData);         

    // Close everything.
    stream.Close();         
    client.Close();         
  } 
  catch (ArgumentNullException e) 
  {
    Console.WriteLine("ArgumentNullException: {0}", e);
  } 
  catch (SocketException e) 
  {
    Console.WriteLine("SocketException: {0}", e);
  }
    
  Console.WriteLine("\n Press Enter to continue...");
  Console.Read();
}

//引入命名空间
using System;
using System.IO;
using System.Net.Sockets;

class MainClass
{
  const int echoPort = 7;

  [STAThread]
  static void Main(string[] args)
  {
    using ( TcpClient tc = new TcpClient( "localhost", echoPort ) )
    {
      NetworkStream ns = tc.GetStream();
      StreamWriter sw = new StreamWriter( ns );
      StreamReader sr = new StreamReader( ns );

      sw.WriteLine( "test message" );
      sw.Flush();
      System.Console.WriteLine( sr.ReadLine() );
    }
  }
}