C#根據url網址獲取htm文檔的title標題

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Net;
  
namespace test_for_title
{
    class Program
    {
        static string GetHtml(string url, Encoding encoding)
        {
            byte[] buf = new WebClient().DownloadData(url);
            if (encoding != null) return encoding.GetString(buf);
            string html = Encoding.UTF8.GetString(buf);
            if (encoding == null || encoding == Encoding.UTF8)
                return html;
            return encoding.GetString(buf);
        }
  
        static string GetTitle(string html)
        {
            string pattern = @"(?si)<title(?:\s+(?:""[^""]*""|'[^']*'|[^""'>])*)?>(?<title>.*?)</title>";
            return Regex.Match(html, pattern).Groups["title"].Value.Trim();
        }
        
        static void PrintTitle(string url)
        {
            string html = GetHtml(url, null);
            Console.WriteLine("頁面的title為：\n"+GetTitle(html));          
        }
  
        static void Main(string[] args)
        {
            PrintTitle("http://hovertree.net");
            Console.Read();
        }
    }
}