XmlWriter encoding issues

Question

I have the following code:

    MemoryStream ms = new MemoryStream();
    XmlWriter w = XmlWriter.Create(ms);

    w.WriteStartDocument(true);
    w.WriteStartElement("data");

    w.WriteElementString("child", "myvalue");

    w.WriteEndElement();//data
    w.Close();
    ms.Close();

    string test = UTF8Encoding.UTF8.GetString(ms.ToArray());

The XML is generated correctly; however, my problem is the first character of the string 'test' is ï (char #239), making it invalid to some xml parsers: where is this coming from? What exactly am I doing incorrectly?

I know I can resolve the issue by just starting after the first character, but I'd rather know why it's there than simply patching over the problem.

Thanks!

Answer 1

You can change encodings like this:

w.Settings.Encoding = Encoding.UTF8;

Answer 2

Check

• XMLTextWriter Encoding problem
• XmlWriter, Strings and Byte Order Marks

Answer 3

The problem is that your the XML generated by the writer is UTF-16 while you use UTF-8 to convert it to string. Try this instead:

StringBuilder sb = new StringBuilder();
using (StringWriter writer = new StringWriter(sb))
using (XmlWriter w = XmlWriter.Create(writer))
{
    w.WriteStartDocument(true);
    w.WriteStartElement("data");

    w.WriteElementString("child", "myvalue");

    w.WriteEndElement();//data
}

string test = sb.ToString();

Answer 4

Found one solution here: http://www.timvw.be/generating-utf-8-with-systemxmlxmlwriter/

I was missing this at the top:

XmlWriterSettings xmlWriterSettings = new XmlWriterSettings();
xmlWriterSettings.Encoding = new UTF8Encoding(false);
MemoryStream ms = new MemoryStream();
XmlWriter w = XmlWriter.Create(ms, xmlWriterSettings);

Thanks for the help everyone!

Answer 5

All of these are slightly off, if you care about the byte order mark which is something editors use (such as Visual Studio detecting UTF8 encoded XML and syntax highlighting properly).

Here's a solution:

MemoryStream stream = new MemoryStream();

XmlWriterSettings settings = new XmlWriterSettings();
settings.Encoding = Encoding.UTF8;
settings.Indent = true;
settings.IndentChars = "\t";

using (XmlWriter writer = XmlWriter.Create(stream, settings))
{
    // ... write

    // Make sure you flush or you only get half the text
    writer.Flush();

    // Use a StreamReader to get the byte order correct
    StreamReader reader = new StreamReader(stream,Encoding.UTF8,true);
    stream.Seek(0, SeekOrigin.Begin);
    result = reader.ReadToEnd();
}

I've got 2 snippets in full here