private void button1_Click(object sender, EventArgs e)
        {
            string file, dir;
            dir = Application.StartupPath;
            file = @"20*.shtml";
            string reg = @"\<a href=""/quanzi/index\.aspx\?digest=\d""\>[^\<]+</a>";
            string deletehtml = @"(?s)<.*?>";
            string kcontent = @"(?s)<!--begin content-->(.*?)<!--end content-->";
            //<meta name="description" content="交友：上海 机械及行业设备_0name">
            string d = @"(?<=<meta name=""description"" content="")[^""]+(?="">)";
            ArrayList ar = new ArrayList();
            Ketong.Windows.File.EnumFile(dir,file,ref ar);

            foreach (string s in ar)
            {
                string old = Ketong.Windows.File.Read(s);
                old = Regex.Replace(old, reg, @"<a href=""/quanzi/index.shtml"">业务圈子</a>");
                old = old.Replace("/20071130/", "/20080103/");
                old = old.Replace(@"<a href=""/index.htm"">首页</a>", @"<a href=""/"">首页</a>");
                old = Regex.Replace(old,@"\<body onLoad=""pageOnLoad\(\d+\)""\>","<body>");
                old = old.Replace("0name","交友").Replace("1name","求职").Replace("2name","招聘").Replace("3name","QQ业务群");
                string varcontent = Regex.Match(old, kcontent).Groups[1].Value;
                varcontent = Regex.Replace(varcontent, deletehtml, "").Replace("\r\n", "").Replace(" ", "").Replace("　","");
                if (varcontent.Length >= 80)
                    varcontent = varcontent.Substring(0, 80);
                old = Regex.Replace(old, d, varcontent);
                Ketong.Windows.File.Create(s, old);
            }

http://www.microsoftdoc.com/article/66.html