c# 去除文本的html标签

 public static string ContentReplace(string input)
         {
             input = Regex.Replace(input, @"<(.[^>]*)>", "", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"([\r\n])[\s]+", "", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"-->", "", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"<!--.*", "", RegexOptions.IgnoreCase);

             input = Regex.Replace(input, @"&(quot|#34);", "\"", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"&(amp|#38);", "&", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"&(lt|#60);", "<", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"&(gt|#62);", ">", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"&(nbsp|#160);", " ", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"&(iexcl|#161);", "\xa1", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"&(cent|#162);", "\xa2", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"&(pound|#163);", "\xa3", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"&(copy|#169);", "\xa9", RegexOptions.IgnoreCase);
             input = Regex.Replace(input, @"&#(\d+);", "", RegexOptions.IgnoreCase);

             input.Replace("<", "");
             input.Replace(">", "");
             input.Replace("\r\n", "");
             //去两端空格，中间多余空格
             input = Regex.Replace(input.Trim(), "\\s+", " ");
             return input;
         }