在c#编程中怎样获取未知文档的编码方式

没有直接的方法，只能通过判断前面几个字节来实现
private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Filter = "文件文档|*.txt";
            if (ofd.ShowDialog() == DialogResult.OK)
            {
                string fileName = ofd.FileName;
                FileInfo file = new FileInfo(fileName);
                FileStream stream = new FileStream(fileName, FileMode.Open, FileAccess.Read);
                BinaryReader reader = new BinaryReader(stream);
                byte[] b = reader.ReadBytes(3);
                string s = "";
                for (int i = 0; i < b.Length; i++)
                {
                    s += Convert.ToInt32(b[i].ToString()).ToString("X");
                }
                reader.Close();
                if (s.Contains("EFBBBF"))
                    MessageBox.Show("UTF - 8");
                else if (s.Contains("FFFE"))
                    MessageBox.Show("Unicode");
                else if (s.Contains("FEFF"))
                    MessageBox.Show("Unicode big endian");
                else
                    MessageBox.Show("ANSI");
            }
        }

前面三种编码是有规律的，ANSI找不出规律来

二楼
谢了

学习了。