正则表达式去更改

string test = "asdfasf<a href=\"dadfa\">adfasdf</a>adsfa<a href=\"fdsafa\">fdsafas</a><a href=\"fdfdasf\">adsfsafasf</a>";
            string aa = Regex.Replace(test, @"<a [^>]+>", "<a href=\"#\">");
            Response.Write(aa);
运行结果如下:
asdfasf<a href="#">adfasdf</a>adsfa<a href="#">fdsafas</a><a href="#">adsfsafasf</a>