How can I pull out the XML namespace prefix from an XElement object?

Question

I have an XElement object pulled out of an XDocument object, for example

XDocument doc = XDocument.Parse(@"<billpg:MyRoot xmlns:billpg=""http://billpg.com/rutabaga"" />");
XElement elem = doc.Root; /* Or any element inside the document. */

How can I pull out the XML prefix from this XElement object?
(In the above example for elem is "billpg".)

I can get the full URL namespace from elem.Name.Namespace.NamespaceName , but I'm trying to pull out the short "billpg" part instead. I'll also note that elem.ToString() returns a string that includes "billpg" in the right place which could probably be regex'd out. While this would work, its not really in the spirit of using an XML library.

Answer 1

Use the GetPrefixOfNamespace() method to achieve this:

var prefix = elem.GetPrefixOfNamespace(elem.Name.Namespace);

More info on this you can find in the documentation: https://docs.microsoft.com/en-us/dotnet/api/system.xml.linq.xelement.getprefixofnamespace