C# in a Nutshell, Second Edition

Parsing an XML Stream

Of course, simply reading and writing XML in this form, while of some use, is somewhat limiting. Much of XML’s attraction is in its ability to provide structure over data; using XmlReader “in the raw,” however, hides the very hierarchical structure XML imposes. In many cases, XML data is best viewed as an arranged tree of data, complete with the XML structuring elements (the tags and attributes surrounding the data) found within it.

Fortunately, the .NET XML architecture supports such a view, using the XmlDocument class to model the entire XML document itself. To see the hierarchical structure in an XML document, you must first pass the XML into the XmlDocument instance for parsing:

XmlDocument doc = new XmlDocument( );
doc.Load(new XmlReader(...));

Alternatively, you can use LoadXml to parse an arbitrary string instance.

Once the XmlDocument is populated with data, the document’s document element can be obtained from the XmlDocument instance via the DocumentElement property. From there, it is a simple matter to walk the various child nodes, all the way to the elements of interest:

XmlNode docNode = doc.DocumentElement;
//print out all the first-level children
foreach (XmlNode n in docNode.ChildNodes)
  System.Console.WriteLine(n.Name);

At this point, navigation becomes an exercise in using the various properties and methods on XmlNode. The Attributes property returns an XmlAttributeCollection containing the attributes (if any) on this node, the ChildNodes property ...