class Program    {        static void Main(string[] args)        {            string input = "白日依山尽，黄河入海流。欲穷千里目，更上一层楼。";            IStringInverter inverter1 = new StringInverter1();            string str1 = inverter1.PiecewiseInvert(input);            Console.WriteLine(str1);            IStringInverter inverter2 = new StringInverter2();            string str2 = inverter2.PiecewiseInvert(input);            Console.WriteLine(str2);            Console.Read();        }    }    /// 
    /// 根据标点符号反转    /// 
    class StringInverter1 : IStringInverter    {        #region IStringInverter 成员        public string PiecewiseInvert(string input)        {            StringBuilder sb = new StringBuilder();            int spindex = input.IndexOf('。');            for (int i = 0; i < input.Length; i++)            {                if (spindex > -1)                {                    if (input[i] != '。')                    {                        sb.Append(input[spindex - i - 1]);                    }                    else                    {                        i -= (spindex + 1);                        input = input.Remove(0, spindex + 1);                        spindex = input.IndexOf('。');                        sb.Append('。');                    }                }                else                {                    sb.Append(input[input.Length - i - 1]);                }//每句反转                         }            string[] two = sb.ToString().Split('。', '，');            if (two.Length > 3)                return two[1] + "，" + two[0] + "。" + two[3] + "，" + two[2] + "。";            else                throw new ArgumentException("此方法只能处理**，**。的语句");        }        #endregion    }    /// 
    /// 利用正则，3种方法反转字符串    /// 
    class StringInverter2 : IStringInverter    {        #region IStringInverter 成员        public string PiecewiseInvert(string input)        {            Regex punctuationReg = new Regex(@"[，。]");            MatchCollection matchs = punctuationReg.Matches(input);            StringBuilder sb = new StringBuilder();            for (int i = 0; i < matchs.Count; i++)//匹配出有多少段            {                int index = input.IndexOf(matchs[i].Value);                string section = input.Remove(index);                input = input.Remove(0, index + 1);                #region  遍历一半,利用临时变量                var tempchars = section.ToCharArray();                int templen = tempchars.Length;                for (int c = 0; c < templen / 2; c++)                {                    char temp = tempchars[c];                    tempchars[c] = tempchars[templen - c - 1];                    tempchars[templen - c - 1] = temp;                }                section = string.Join("", tempchars);                sb.Append(section);                #endregion                #region 遍历一遍                //for (int c = 0; c < section.Length; c++)                //{                //    sb.Append(section[section.Length - c - 1]);//反转每句                //}                #endregion                #region array的静态方法反转                //var chars = section.ToCharArray();                //Array.Reverse(chars);                //section = string.Join("", chars);                //sb.Append(section);                #endregion                sb.Append(matchs[i].Value);//加上标点            }            return sb.ToString();        }        #endregion    }    interface IStringInverter    {        string PiecewiseInvert(string input);    }