Tim Van Wassenhove

Passionate geek, interested in Technology. Proud father of two

08 Jan 2007

Generating UTF-8 with System.Xml.XmlWriter

Today i decided to experiment with XmlWriter. The first i wanted to do was set the Encoding to UTF-8.

StringBuilder stringBuilder = new StringBuilder();
XmlWriter xmlWriter = XmlWriter.Create(stringBuilder);
xmlWriter.Settings.Encoding = Encoding.UTF8;

When i ran this code i recieved the following exception: XmlException was unhandled: The ‘XmlWriterSettings.Encoding’ property is read only and cannot be set. The documentation for the Settings property clearly says

The XmlWriterSettings object returned by the Settings property cannot be modified. Any attempt to change individual settings results in an exception being thrown.

So i wrote the following

StringBuilder stringBuilder = new StringBuilder();
XmlWriterSettings xmlWriterSettings = new XmlWriterSettings();
xmlWriterSettings.Encoding = Encoding.UTF8;

XmlWriter xmlWriter = XmlWriter.Create(stringBuilder, xmlWriterSettings);
xmlWriter.WriteStartDocument();
xmlWriter.WriteStartElement("root", "http://www.timvw.be/ns");
xmlWriter.WriteEndElement();
xmlWriter.WriteEndDocument();
xmlWriter.Flush();
xmlWriter.Close();

string xmlString = stringBuilder.ToString();

As you can see: is still not what i want. Apparently is the Encoding property ignored if the XmlWriter is not using a Stream. So here is my next attempt

MemoryStream memoryStream = new MemoryStream();
// initialize xmlWriterSettings as above...

XmlWriter xmlWriter = XmlWriter.Create(memoryStream, xmlWriterSettings);
// call the same operations on the xmlWriter as above...

string xmlString = Encoding.UTF8.GetString(memoryStream.ToArray());

Ok, i’m getting close: ?. Luckily enough i knew that the ? (byte with value 239) at the beginning is the BOM. In order to get rid of that byte i had to create my own instance of UTF8Encoding. Finally, i can present some working code

MemoryStream memoryStream = new MemoryStream();
XmlWriterSettings xmlWriterSettings = new XmlWriterSettings();
xmlWriterSettings.Encoding = new UTF8Encoding(false);
xmlWriterSettings.ConformanceLevel = ConformanceLevel.Document;
xmlWriterSettings.Indent = true;

XmlWriter xmlWriter = XmlWriter.Create(memoryStream, xmlWriterSettings);
xmlWriter.WriteStartDocument();
xmlWriter.WriteStartElement("root", "http://www.timvw.be/ns");
xmlWriter.WriteEndElement();
xmlWriter.WriteEndDocument();
xmlWriter.Flush();
xmlWriter.Close();

string xmlString = Encoding.UTF8.GetString(memoryStream.ToArray());