2012.6.7正則表達式 分組用法

Regex rx = new Regex(@"[A-Z0-9a-z\.\-_]+@([a-z0-9]+)\.[a-z0-9A-z]");
            string html = File.ReadAllText("1.htm");
            //提取Email,
            //通過()提取組。
         
            //fd(s(a(fds)a)f)sf(d(s(af)d)s)a
            MatchCollection mc = rx.Matches(html, 0);
            //請統計出常用郵件服務提供商的用戶使用。
            //163
            //sohu
            //gmail
            //qq
            int count_163 = 0;
            int count_gmail = 0;
            int count_qq = 0;

foreach (Match match in mc)
            {
               

//通過match.Groups[]來獲取提取組。注意：第0組存儲的是完整匹配字符串，要獲取組因該從索引1開始。
                switch (match.Groups[1].Value.ToLower())
                {
                    case "163":
                        count_163++;
                        break;
                    case "gmail":
                        count_gmail++;
                        break;
                    case "qq":
                        count_qq++;
                        break;
                }
            }
            Console.WriteLine(mc.Count);
            Console.WriteLine("網易郵箱用戶數：{0}", count_163);
            Console.WriteLine("gmail郵箱用戶數：{0}", count_gmail);
            Console.WriteLine("qq郵箱用戶數：{0}", count_qq);

分組替換

string msg = "234--234--------------34-55";
            Regex remsg=new Regex(@"(\-)+");
            msg=remsg.Replace(msg,"-");
            Console.WriteLine(msg);


            string msg1 = "我的生日是05/21/2010耶";

            Regex remsg1 = new Regex(@"(\d{1,2})\/(\d{1,2})\/(\d{4})");

            msg1 = remsg1.Replace(msg1, "$3-$2-$1");
            Console.WriteLine(msg1);