C#FileStrea读写

      //FileStream 操作字节的
      //StreamReader和StreamWriter 操作字符的
      FileStream fsRead = new FileStream(@"C:\Users\admin\Desktop\av.txt", FileMode.OpenOrCreate, FileAccess.Read);
      byte[] buffer = new byte[1024 * 1024 * 5];
      fsRead.Read(buffer, 0, buffer.Length);
      //返回本次实际读取到的有效字节数
      int r = fsRead.Read(buffer, 0, buffer.Length);
      //将字节数组中每一个元素按照指定的编码格式解成字符串
      string s = Encoding.Default.GetString(buffer,0,r);
      //关闭流
      fsRead.Close();
      //释放流所占用的资源
      fsRead.Dispose();
      Console.WriteLine(s);
      Console.ReadKey();


      //使用FileStream来写入数据
      using (FileStream fswrite = new FileStream(@"C:\Users\admin\Desktop\av.txt", FileMode.OpenOrCreate, FileAccess.Write))
      {

          string str = "看我有没有把你覆盖掉";
          byte[] buff = Encoding.Default.GetBytes(str);
          fswrite.Write(buff, 0, buff.Length);
          
      
      
      }

      Console.WriteLine("写入成功");
      Console.ReadKey();