不用冒泡算法，将一串只包含数字字符的字符串从小到大进行排序

/// <summary>
        /// 将一串只包含数字字符的字符串从小到大进行排序
        /// </summary>
        /// <param name="IntStr"></param>
        /// <returns></returns>
        public static string SortIntStr(string IntStr)
        {
            try
            {
                string ReturnStr = "";
                List<int> IntArr = new List<int>();
                for (int i = 0; i < IntStr.Length; i++)
                {
                    IntArr.Add(int.Parse(IntStr.Substring(i, 1)));
                }
                IntArr.Sort(delegate(int x, int y) { return x.CompareTo(y); });

                foreach (int k in IntArr)
                {
                    ReturnStr += k.ToString();
                }
                return ReturnStr;
            }
            catch
            {
                return IntStr;
            }
        }