C#正则表达式分组使用

           string s = "dfasfdasfdsa*fdasfdsafdsa";
            s = "转发:dfasfdasfdsa*fdasfdsafdsa";
            //s = "转发:***dfasfdasfdsa*fdasfdsafdsa";
            //s = "转发: dfasfdasfdsa*fdasfdsafdsa";
            //s = "转发: * * * dfasfdasfdsa*fdasfdsafdsa";

            MatchCollection mc = Regex.Matches(s, @"(转发:)*[s|*]*(?<a>S+)");
            foreach (Match m in mc)
            {
                string s2 = m.Groups["a"].Value;
                //s2 = dfasfdasfdsa*fdasfdsafdsa
            }     

分组中我们使用(?<a>S+)表示一组