Why am I getting an extra character (a dot or bullet point) at the beginning of my byte array?

Question

I have the following code used to get xml from a DataSet into a byte array using UTF-8 encoding:

private static byte[] fGetXmlBytes(DataTable lvDataTable)
{
  XmlWriterSettings lvSettings = new XmlWriterSettings();
  lvSettings.Encoding = Encoding.UTF8;
  lvSettings.NewLineHandling = NewLineHandling.Replace;
  lvSettings.NewLineChars = String.Empty;

  using(MemoryStream lvMemoryStream = new MemoryStream())
  using (XmlWriter lvWriter = XmlWriter.Create(lvMemoryStream, lvSettings))
  {
    lvDataTable.WriteXml(lvWriter, XmlWriteMode.IgnoreSchema);
    //Lines used during debugging
    //byte[] lvXmlBytes = lvMemoryStream.GetBuffer();
    //String lsXml = Encoding.UTF8.GetString(lvXmlBytes, 0, lvXmlBytes.Length);
    return lvMemoryStream.GetBuffer();
  }
}

I want a byte array because I subsequently pass the data to compression and encryption routines that work on byte arrays. Problem is I end up with an extra character at the start of the xml. Instead of:

<?xml version="1.0" encoding="utf-8"?><etc....

I get

.<?xml version="1.0" encoding="utf-8"?><etc....

Does anyone know why the character is there? Is there a way to prevent the character being added? Or to easily strip it out?

Colin

Answer 1

Preamble perhaps? Info here: http://www.firstobject.com/dn_markutf8preamble.htm

Answer 2

You will have to use an Encoding class that doesn't emit a preamble. The object returned by Encoding.UTF8 will emit a preamble, but you can create your own UTF8Encoding that doesn't emit a preamble like this:

lvSettings.Encoding = new UTF8Encoding(false);

Answer 3

The extra character is the UTF-8 preamble. AFAIK you cannot prevent the preamble from being written to the stream. However, does it really matter? When the byte array is parsed back into XML, the preamble will be correctly interpreted without error, so you might as well just leave it in there.

Answer 4

I am doing mostly the same with this code and it works perfectly:

MemoryStream data = new MemoryStream(1000);
datatable.WriteXml(data);
return data.toArray();