我可以使用C＃获得XML TagName的独特列表吗？

Question

I have a very long xml file and I need to identify what are the distinct TagName in that xml file. I wonder if I can get it in my C# application with XmlDocument library.

In this example xml, I want to find all the TagName: bookstore, book genre, title, first name

<bookstore>
  <book genre="novel">
    <title>The Autobiography of Benjamin Franklin</title>    
  </book>
  <book genre="novel">
    <title>The Confidence Man</title>
    <first-name>Herman</first-name>
  </book>
</bookstore>

Answer 1

Parse it as an XDocument and you could do this:

var names = doc.Descendants().Select(e => e.Name.LocalName).Distinct();

This will give you the results (in some order):

bookstore 
book 
title 
first-name 

Otherwise if you must use an XmlDocument , you could do this:

var names =  doc.DocumentElement
    .SelectNodes("//*").Cast<XmlNode>()
    .Select(e => e.LocalName)
    .Distinct();

Answer 2

You can use HashSet to get distinct names. Moreover, it is very fast.

var doc = XDocument.Load("test.xml");
var set = new HashSet<string>();

foreach (var node in doc.Descendants())
{
    set.Add(node.Name.LocalName);

    foreach (var attr in node.Attributes())
        set.Add(attr.Name.LocalName);
}

foreach (var name in set)
    Console.WriteLine(name);