文件读写，尝试filestream和streamreader，streamwriter

将文件11.txt读出来，再写入11_副本.txt里面。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            FileStream aFile = new FileStream(@"C:UsersAdministratorDesktop11.txt",FileMode.OpenOrCreate);
            StreamReader aa = new StreamReader(aFile);
            FileStream bFile = new FileStream(@"C:UsersAdministratorDesktop11_副本.txt", FileMode.OpenOrCreate);
            StreamWriter bb = new StreamWriter(bFile);
            string res = aa.ReadLine();
           
            while (res != null)
            {
                bb.WriteLine(res);
                res = aa.ReadLine();
            }
            aa.Close();
            aFile.Close();
            bb.Close();
            bFile.Close();
            
        }

    }
}