读取文件的代码
            byte [] byData=new byte[300];
            char [] charData=new char[300];
            FileStream sfile = new FileStream("writedata.txt", FileMode.Open);
            sfile.Seek(0, SeekOrigin.Begin);
            sfile.Read(byData, 0, byData.Length);            Decoder d = Encoding.UTF8.GetDecoder();
            d.GetChars(byData, 0, byData.Length, charData, 0);
            sfile.Close();            string allstr = charData.ToString();
            textBox1 .Text = allstr;但是读取出来的是:System.Char[]why?