using System;
// Declare delegate -- defines required signature:
delegate void SampleDelegate(string message);
class MainClass
{
    // Regular method that matches signature:
    static void SampleDelegateMethod(string message)
    {
        Console.WriteLine(message);
    }
    static void Main()
    {
        // Instantiate delegate with named method:
        SampleDelegate d1 = SampleDelegateMethod;
        // Instantiate delegate with anonymous method:
        SampleDelegate d2 = delegate(string message)
        {
            Console.WriteLine(message);
        };
        // Invoke delegate d1:
        d1("Hello");
        // Invoke delegate d2:
        d2(" World");
    }
}
        

C#物件 事件 委派 撰寫 範例
using System;
using System.Collections.Generic;
using System.Text;
namespace eventSimple
{
    class Program
    {
        delegate void myFunction(string text);
        static event myFunction readKeyEvent;
        static void Main(string[] args)
        {
            readKeyEvent += new myFunction(myFunction1);
            Console.WriteLine("請輸入一字串");
            string text = Console.ReadLine();
            Console.WriteLine();
            Console.WriteLine("第一次觸發事件");
            readKeyEvent.Invoke(text);
            Console.WriteLine();
            readKeyEvent += new myFunction(myFunction2);
            Console.WriteLine("請輸入一字串");
            text = Console.ReadLine();
            Console.WriteLine();
            Console.WriteLine("第二次觸發事件");
            readKeyEvent.Invoke(text);
            Console.WriteLine();
            Console.WriteLine("按任意鍵離開");
            Console.ReadKey();
        }
        static void myFunction1(string text)
        {
            Console.WriteLine("這次第一次執行的函數");
            Console.WriteLine("參數="+text);
        }
        static void myFunction2(string text)
        {
            Console.WriteLine("這次第二次執行的函數");
            Console.WriteLine("參數=" + text);
        }
      }
}
        

　　public void UseSqlReader()
　　{
　　　SqlConnection sqlConnection = new SqlConnection(sqlConnectionCommand);
　　　SqlCommand sqlCommand = new SqlCommand();
　　　sqlCommand.CommandType = System.Data.CommandType.Text;
　　　sqlCommand.Connection = sqlConnection;
　　　sqlCommand.CommandText = sqlSelectCommand;
　　　sqlConnection.Open();
　　　SqlDataReader sqlDataReader = sqlCommand.ExecuteReader();
　　　while(sqlDataReader.Read())
　　　{
　　　　//Get KeywordID and KeywordName , You can do anything you like. Here I just output them.
　　　　int keywordid = (int)sqlDataReader[0];
　　　　//the same as: int keywordid = (int)sqlDataReader["KeywordID"]
　　　　string keywordName = (string)sqlDataReader[1];
　　　　//the same as: string keywordName = (int)sqlDataReader["KeywordName"]
　　　　Console.WriteLine("KeywordID = " + keywordid + " , KeywordName = " + keywordName);
　　　}
　　　sqlDataReader.Close();
　　　sqlCommand.Dispose();
　　　sqlConnection.Close();
　　}
        

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Net;
using System.Text.RegularExpressions;
class WebCrawler
{
//    WebProxy proxy = new WebProxy("http://proxy.internal:3128/", true);
    List<String> urlList = new List<String>();
    // Dictionary<String, String> 
    public static void Main(String[] args)
    {
        WebCrawler crawler = new WebCrawler();
        crawler.urlList.Add("http://tw.msn.com/");
        crawler.craw();
    }
    public void craw()
    {
        int urlIdx = 0;
        while (urlIdx < urlList.Count)
        {
            try
            {
                String url = urlList[urlIdx];
                String fileName = "data/" + toFileName(url);
                Console.WriteLine(urlIdx + ":url=" + url + " file=" + fileName);
                urlToFile(url, fileName);
                String html = fileToText(fileName);
                foreach (String childUrl in matches("\\shref\\s*=\\s*\"(.*?)\"", html, 1))
                {
                    Console.WriteLine(childUrl);
                    urlList.Add(childUrl);
                }
            }
            catch
            {
                Console.WriteLine("Error:" + urlList[urlIdx] + " fail!");
            }
            urlIdx++;
        }
    }
    public static IEnumerable matches(String pPattern, String pText, int pGroupId)
    {
        Regex r = new Regex(pPattern, RegexOptions.IgnoreCase | RegexOptions.Compiled);
        for (Match m = r.Match(pText); m.Success; m = m.NextMatch())
         yield return m.Groups[pGroupId].Value;
    }
    public static String fileToText(String filePath)
    {
        StreamReader file = new StreamReader(filePath);
        String text = file.ReadToEnd();
        file.Close();
        return text;
    }
    public void urlToFile(String url, String file)
    {
        WebClient webclient = new WebClient();
//        webclient.Proxy = proxy;
        webclient.DownloadFile(url, file);
    }
    public static String toFileName(String url)
    {
        String fileName = url.Replace('?', '_');
        fileName = fileName.Replace('/', '_');
        fileName = fileName.Replace('&', '_');
        fileName = fileName.Replace(':', '_');
        fileName = fileName.ToLower();
        if (!fileName.EndsWith(".htm") && !fileName.EndsWith(".html"))
         fileName = fileName + ".htm";
        return fileName;
    }
}
        

using System;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Text;
// HttpClient http://ccckmit.wikidot.com/ teach teach.htm
public class HttpClient
{
    public static void Main(string[] args)
    {
        // download("tw.msn.com", "/", "msn.htm");
        download("127.0.0.1", "/index.htm", "localindex.htm");
    }
    public static void download(String site, String path, String toFileName)
    {
/*        IPHostEntry hostEntry = Dns.GetHostEntry(site);
        foreach (IPAddress addr in hostEntry.AddressList)
        {
            Console.WriteLine("address = "+addr);
        }
        IPAddress ipAddress = hostEntry.AddressList[0];
//        IPEndPoint ipep = new IPEndPoint(ipAddress, 80);
 */
        IPEndPoint ipep = new IPEndPoint(IPAddress.Parse(site), 80);
        //        IPEndPoint ipep = new IPEndPoint(ipAddress, 80);
        Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        server.Connect(ipep);
        String head = "GET " + path + " HTTP/1.0\n\n";
        byte[] headbuf = Encoding.UTF8.GetBytes(head);
        server.Send(headbuf);
        NetworkStream stream = new NetworkStream(server);
        StreamReader reader = new StreamReader(stream);
        int contentLength = 0;
        while (true)
        {
            String line = reader.ReadLine();
            if (line.StartsWith("Content-Length:"))
                contentLength = int.Parse(line.Substring("Content-Length:".Length));
            Console.WriteLine(line);
            if (line.Length == 0) break;
        }
        byte[] buf = new byte[contentLength];
        reader.ReadBlock(buf, 0, contentLength);
        FileStream outFile = new FileStream(toFileName, System.IO.FileMode.Create, System.IO.FileAccess.Write);
        outFile.Write(buf, 0, buf.Length);
        outFile.Close();
        server.Shutdown(SocketShutdown.Both);
        server.Close();
    }
}
        

using System;
using System.IO;
using System.Net;
class UrlDownloader
{
    public static void Main(String[] args)
    {
        Console.WriteLine(args[0]);
        UrlToFile(args[0], args[1]);
    }
    public static void UrlToFile(String url, String file)
    {
        WebClient webclient = new WebClient();
        webclient.DownloadFile(url, file);
    }
}
        

using System;
using System.IO;
using System.Net;
class WebCrawler
{
    public static void Main(String[] args)
    {
        String text = fileToText(args[0]);
        String[] urls = text.Split('\n');
        for (int i = 0; i < urls.Length; i++)
        {
         Console.WriteLine(i + ":" + urls[i]);
         UrlToFile(urls[i], i+".htm");
        }
//     Console.WriteLine(text);
    }
    public static String fileToText(String filePath)
    {
        StreamReader file = new StreamReader(filePath);
        String text = file.ReadToEnd();
        file.Close();
        return text;
    }
    public static void UrlToFile(String url, String file) {
        WebClient webclient = new WebClient();
        webclient.DownloadFile("http://"+url, file);
    }
}
        

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.IO;
public class HttpServer
{
    public static void Main()
    {
        IPEndPoint ipep = new IPEndPoint(IPAddress.Any, 80);
        Socket newsock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        newsock.Bind(ipep);
        newsock.Listen(10);
        while(true)
        {
         Socket client = newsock.Accept();
         IPEndPoint clientep = (IPEndPoint) client.RemoteEndPoint;
         // create a new thread and then receive message.
         HttpListener listener = new HttpListener(client);
         Thread thread = new Thread(new ThreadStart(listener.run));
         thread.Start();
        }
//      newsock.Close();
   }
}
public class HttpListener {
    Socket socket;
    public HttpListener(Socket s)
    {
        socket = s;
    }
    public void run() 
    {
        String msg = "Hello!";
        String helloMsg = @"HTTP/1.0 200 OK\nContent-Type: text/plain\nContgent-Length: "+msg.Length+"\n\n"+msg;
        NetworkStream stream = new NetworkStream(socket);
        StreamReader reader = new StreamReader(stream);
        String header = "";
        while (true) 
        {
         String line = reader.ReadLine();
         Console.WriteLine(line);
         if (line.Trim().Length==0)
         break;
         header += line+"\n";
        }
        socket.Send(Encoding.UTF8.GetBytes(helloMsg));
        socket.Close();
    }
}
        

// ---------------------------------------------------------------
// 共有五個程式檔案
//
//  程式檔 : ChatLib.cs
//  程式檔 : ChattServer.cs
//  程式檔 : WinChatClient.cs
//  程式檔 : FormChatClient.cs
//  程式檔 : FormChatClient.Designer.cs
//
// 編譯方式 : 
//    步驟 1 : csc ChatServer.cs ChatLib.cs
//             會產生 ChatServer.exe 檔
//
//    步驟 2 : csc WinChatClient.cs FormChatClient.cs FormChatClient.Designer.cs ChatLib.cs
//             會產生 WinChatClient.exe 檔
//     
// 執行方式 : 
//    步驟 1 : 執行 ChatServer.exe
//    步驟 2 : 執行 WinChatClient.exe (使用者 1)
//    步驟 3 : 執行 WinChatClient.exe (使用者 2)
//
// 如此，兩個 WinChatClient.exe 的視窗間即可透過本機聊天
// ---------------------------------------------------------------