Question

StringBuilder output = new StringBuilder();
using (XmlWriter writer = XmlWriter.Create(output))
{
    writer.WriteStartElement("test");
    writer.WriteCData("taco\vbell");
    writer.WriteEndElement();
    writer.WriteEndDocument();
}

Console.WriteLine(output.ToString());

WriteCData throws the following ArgumentException, “‘\v’, hexadecimal value 0x0B, is an invalid character”

I thought CData can take any kind of data. Since this is not the case, what characters do I have to escape? Thanks.

Answer 1

No, XML itself cannot represent any characters earlier than U+0020 other than tab, carriage return, and line feed.

From the spec, section 2.2:

Character Range

Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF] /* any Unicode character, excluding the surrogate blocks, FFFE, and FFFF. */

There’s no standard way of representing the "forbidden" characters, unfortunately. You’d have to create your own escaping mechanism.