1、首先添加两个windows窗体项目，一个作为服务端server，一个作为客户端Client

2、然后添加服务端代码，添加命名空间，界面上添加TextBox控件

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

3、FormLoad方法添加代码

private void Form1_Load(object sender, EventArgs e)
        {
            IPEndPoint epServer = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 7878);//IP地址和端口号
            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);//定义socket
            socket.Bind(epServer);//绑定
            socket.Listen(10);//监听
            socket.BeginAccept(new AsyncCallback(RecVing), socket);//异步接收，回调方法为RecVing
        }

4、添加回调方法代码

private void RecVing(IAsyncResult rec_socket)
        {
            string cmdstr = "";
            Socket sc = (Socket)rec_socket.AsyncState;
            Socket socket = sc.EndAccept(rec_socket);
            byte[] bytes = new byte[1024];
            int i = socket.Receive(bytes);
            cmdstr = Encoding.UTF8.GetString(bytes, 0, i);
            showstrs(cmdstr);
            sc.BeginAccept(new AsyncCallback(RecVing), sc);
        }

5、添加showstrs方法，

定义委托private delegate void shixudong_invoke(string invokefun);

private void showstrs(string recv_strs)
        {
            if (recv_strs.Length != 0)
            {
                if (this.InvokeRequired)
                {
                    shixudong_invoke invoke = new shixudong_invoke(showstrs);
                    this.Invoke(invoke, (object)recv_strs);
                }
                else
                {
                    textBox1.Text = recv_strs;
                }
            }

6、到此为止，服务端已经添加完毕

7，客户端代码，首先跟服务端一样，添加命名空间，在界面上添加button事件

private void button1_Click(object sender, EventArgs e)
        {
            IPEndPoint IPEndPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 7878);//IP，端口号
            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            socket.BeginConnect(IPEndPoint, new AsyncCallback(Sending), socket);//回调方法Sending
        }

8、添加回调方法，代码如下

private void Sending(IAsyncResult rec_socket)
        {
            Socket socket = (Socket)rec_socket.AsyncState;
            try
            {
                if (socket.Connected)
                {
                    byte[] msgBuff = Encoding.UTF8.GetBytes(textBox1.Text);
                    socket.Send(msgBuff);
                    //socket.Accept();
                }
                else
                {
                    Console.WriteLine("Error!", "Error!");
                }
            }
            catch
            {
                Console.WriteLine("Error!", "Error!");
            }

9、到此为止，客户端代码已经完成，调试的时候先启动服务端，然后启动客户端

10、运行截图如下，点击按钮前，在文本框中输入shixudong