How to add a document type to a new XML file in C#

Question

How do I add the following document type to the begining of an XML file

<!DOCTYPE smil PUBLIC "-//W3C//DTD SMIL 2.0//EN" "http://www.w3.org/2001/SMIL20/SMIL20.dtd">

I am trying to create an XML file using C# XDocument but cant figure out how to add the above to the beginning of the xml file

Answer 1

You need to add an XDocumentType to the beginning of the XDocument:

var xDocument = new XDocument(
  new XDocumentType(
    "smil",
    "-//W3C//DTD SMIL 2.0//EN",
    "http://www.w3.org/2001/SMIL20/SMIL20.dtd",
    null
  ),
  new XElement("Root")
);