static void Main(string[] args) 
    { 
      TcpClient client = null; 
      NetworkStream stream = null; 
      byte[] buffer = null; 
      string receiveString = null; 
 
      IPAddress localIP = IPAddress.Parse("127.0.0.1"); 
      int localPort = 11000; 
      TcpListener listener = new TcpListener(localIP, localPort);//用本地IP和端口实例化Listener 
      listener.Start();//开始监听 
      while (true) 
      { 
        client = listener.AcceptTcpClient();//接受一个Client 
        buffer = new byte[client.ReceiveBufferSize]; 
        stream = client.GetStream();//获取网络流 
        stream.Read(buffer, 0, buffer.Length);//读取网络流中的数据 
        stream.Close();//关闭流 
        client.Close();//关闭Client 
 
        receiveString = Encoding.Default.GetString(buffer).Trim('\0');//转换成字符串 
        Console.WriteLine(receiveString); 
      } 
    } 

static void Main(string[] args) 
    { 
      string sendString = null;//要发送的字符串 
      byte[] sendData = null;//要发送的字节数组 
      TcpClient client = null;//TcpClient实例 
      NetworkStream stream = null;//网络流 
 
      IPAddress remoteIP = IPAddress.Parse("127.0.0.1");//远程主机IP 
      int remotePort = 11000;//远程主机端口 
 
      while (true)//死循环 
      { 
        sendString = Console.ReadLine();//获取要发送的字符串 
        sendData = Encoding.Default.GetBytes(sendString);//获取要发送的字节数组 
        client = new TcpClient();//实例化TcpClient 
        try 
        { 
          client.Connect(remoteIP, remotePort);//连接远程主机 
        } 
        catch (System.Exception ex) 
        { 
          Console.WriteLine("连接超时，服务器没有响应！");//连接失败 
          Console.ReadKey(); 
          return; 
        } 
        stream = client.GetStream();//获取网络流 
        stream.Write(sendData, 0, sendData.Length);//将数据写入网络流 
        stream.Close();//关闭网络流 
        client.Close();//关闭客户端 
      } 
    } 

static void Main(string[] args) 
    { 
      UdpClient client = null; 
      string receiveString = null; 
      byte[] receiveData = null; 
      //实例化一个远程端点，IP和端口可以随意指定，等调用client.Receive(ref remotePoint)时会将该端点改成真正发送端端点 
      IPEndPoint remotePoint = new IPEndPoint(IPAddress.Any, 0); 
 
      while (true) 
      { 
        client = new UdpClient(11000); 
        receiveData = client.Receive(ref remotePoint);//接收数据 
        receiveString = Encoding.Default.GetString(receiveData); 
        Console.WriteLine(receiveString); 
        client.Close();//关闭连接 
      } 
    } 

static void Main(string[] args) 
    { 
      string sendString = null;//要发送的字符串 
      byte[] sendData = null;//要发送的字节数组 
      UdpClient client = null; 
 
      IPAddress remoteIP = IPAddress.Parse("127.0.0.1"); 
      int remotePort = 11000; 
      IPEndPoint remotePoint = new IPEndPoint(remoteIP, remotePort);//实例化一个远程端点 
 
      while (true) 
      { 
        sendString = Console.ReadLine(); 
        sendData = Encoding.Default.GetBytes(sendString); 
 
        client = new UdpClient(); 
        client.Send(sendData, sendData.Length, remotePoint);//将数据发送到远程端点 
        client.Close();//关闭连接 
      } 
    }