欢迎使用CSDN-markdown编辑器

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3 {
    class Program {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入字符串：");
            int i;
            string mystring = Console.ReadLine();
            Console .WriteLine ("输出后的新的：");
            for (i = mystring.Length - 1; i >= 0; i--)
            {
                Console.Write ("{0}",mystring[i] );
            }
            Console.WriteLine("!");
            Console.ReadKey();
        }
    }
}