Filestream（读写）

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.IO;

namespace 读写文件
{
    class Program
    {
        static void Main(string[] args)
        {
            #region 读取
            FileStream fsRead = new FileStream(@"C:\Users\Administrator\Desktop\毕毕.txt", FileMode.OpenOrCreate, FileAccess.Read);
            //定义字节数组，每次读取多少
            byte[] buffer = new byte[1024 * 1024 * 5];
            int r = fsRead.Read(buffer, 0, buffer.Length);//返回一共读到的有效字节数
            // MessageBox.Show(r.ToString());
            //将字节数组中每一个元素按照指定的编码格式解码成字节串
            string s = Encoding.UTF8.GetString(buffer, 0, r);

            //关闭流
            fsRead.Close();

            //释放流所占用的资源
            //实际上 还是读了5兆  只是显示了所读到的那些
            fsRead.Dispose();
            Console.WriteLine(s);
            Console.ReadLine();
            #endregion

            #region 写入
            //using (FileStream fswrite = new FileStream(@"C:\Users\Administrator\Desktop\毕毕.txt", FileMode.OpenOrCreate, FileAccess.Write))
            //{
            //    //覆盖，覆盖所需占用的字节量
            //    string str = "yes";
            //    byte[] buffer = Encoding.UTF8.GetBytes(str);
            //    fswrite.Write(buffer, 0, buffer.Length);
            //}
            #endregion
        }
    }
}