//StreamRead来读取一个文件
   using (StreamReader sr = new StreamReader(@"C:\Users\enle\Desktop\新建文本文档.txt", Encoding.Default))
   {
    while (!sr.EndOfStream)//循环的去读文件
    {
     Console.WriteLine(sr.ReadLine());
    }
   }
   Console.ReadKey();

//StreamWriter写入一个文本文件
      using (StreamWriter strw = new StreamWriter(@"C:\Users\wbrm\Desktop\新建.txt",true ))//true 表示追加
      {
        //strw.Write("别再能吃苦的年纪选择安逸");
        strw.Write("看我有某有把你覆盖掉");
      }
      Console.WriteLine("写入成功");
      Console.ReadKey();