cxi変換文字列のすべての正則特殊文字方法の例

/// <summary>
        ///               
        /// </summary>
        /// <param name="input">     </param>
        /// <returns></returns>
        string FilterString(string input)
        {
            input = input.Replace("\\", "\\\\");//   “\”，              “\”
            Regex r = new Regex("[\\*\\.\\?\\+\\$\\^\\[\\]\\(\\)\\{\\}\\|\\/]");
            MatchCollection ms = r.Matches(input);
            List<string> list = new List<string>();
            foreach (Match item in ms)
            {
                if (list.Contains(item.Value))
                    continue;
                input = input.Replace(item.Value, "\\" + item.Value);
                list.Add(item.Value);
            }
            return input;
        }