C#中用正则表达示过滤出HTML代码中的所有图片

  string str = "sdfdfd<img name=''src='http://cp.a8.com/image/128X128GIF/50686.gif' width='32' height='32' alt='' />dsfsdfsdf<img name=''src='http://cp.a8.com/image/128X128GIF/53075.gif' width='32' height='32' alt='' />dsfffffffff<img name=''src='http://cp.a8.com/image/128X128GIF/53099.gif' width='32' height='32' alt='' />";
        str += "sdfdfd<img name=''src='http://cp.a8.com/image/128X128GIF/50686.gif' width='32' height='32' alt='' />dsfsdfsdf<img name=''src='http://cp.a8.com/image/128X128GIF/53075.gif' width='32' height='32' alt='' />dsfffffffff<img name=''src='http://cp.a8.com/image/128X128GIF/53099.gif' width='32' height='32' alt='' />";
        Regex r = new Regex("<img.{25,100}/>");
        MatchCollection mc = r.Matches(str);
   
        string[] results = new string[mc.Count];
        for (int i = 0; i < mc.Count; i++)
        {
            results[i]=(mc[i].Value);
     

        }
        // List the results.
        for (int ctr = 0; ctr <= results.Length - 1; ctr++)
        {
            Response.Write( results[ctr]);
            Response.Write("<br>");

        }
        Response.Write(results.Length);