using System;

 using System.Collections.Generic;

 using System.Linq;

 using System.Text;

 using System.Threading.Tasks;

 namespace 临时

 {

     class Program

     {

         static void Main(string[] args)

         {

             //实现改变字符串

             string s = "hello,world!";//新建字符串S并赋值

             char[] chars = s.ToCharArray();//用s.ToCharArray()方法得到字符串的char数组

             chars[] = 'i';//对chars数组进行修改

             s = new string(chars);//调用new string(char[])这个构造函数来创建char数组的字符串

             Console.WriteLine(s);

             Console.ReadKey();

         }

     }

 }