FileStream操作字节 可以操作任何文件

使用FileStream来读取数据

FileStream fsRead = new FileStream(@"C:\Users\TAO\Desktop\new.txt", FileMode.OpenOrCreate, FileAccess.Read);
byte[] buffer = new byte[1024 * 1024 * 5];
//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码成字符串
string s = Encoding.UTF8.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

//将创建文件流对象的过程写在using中，会自动的释放所占用的资源	 
using (FileStream fsWriter = new FileStream(@"C:\Users\TAO\Desktop\new.txt", FileMode.OpenOrCreate, FileAccess.Write)) 
{
     string str = "看我有木有把你覆盖掉";
     byte[] buffer = Encoding.UTF8.GetBytes(str);
     fsWriter.Write(buffer, 0, buffer.Length);
}
Console.WriteLine("ok");
Console.ReadKey();