string path=@"d:\ahua\ceshi.txt";
byte []buf1=new byte[]{1};
FileStream fs=new FileStream(path,FileMode.Open,FileAccess.ReadWrite);
fs.Seek(3,SeekOrigin.Begin);
fs.Write(buf1,0,1);
fs.Flush();
fs.Close();
在该位置上写的是一乱码，郁闷啊！