How to force XDocument to output the prolog in uppercase while preserving identation and formatting?

Question

I want XDocument to output the XML prolog (for example \"\") in uppercase.

Here is how I\'m cur

Answer 1

Here is a sample solution using XmlTextWriter

I am sure there should be a better optimal way..

            XDocument doc = new XDocument(new XDeclaration("1.0", "UTF-8","d"));
            doc.Add(new XElement("MyRoot", "Value blah"));


            using (var str = new StringWriter())
            using (var xmlTextWriter = new XmlTextWriter(str))
            {
                xmlTextWriter.Formatting = Formatting.Indented;
                xmlTextWriter.Indentation = 4;

                xmlTextWriter.WriteRaw(doc.Declaration.ToString().ToUpper());

                foreach (var xElement in doc.Elements())
                {
                   xmlTextWriter.WriteElementString(xElement.Name.ToString(), xElement.Value);
                }

                var finalOutput = str.ToString();
            }

FinalOutput would contain:

Value blah