C# 9.0 in a Nutshell

Chapter 11. Other XML and JSON Technologies

In Chapter 10, we covered the LINQ-to-XML API—and XML in general. In this chapter, we explore the low-level XmlReader/XmlWriter classes and the types for working with JavaScript Object Notation (JSON), which has become a popular alternative to XML.

In the online supplement, we describe the tools for working with XML schema and stylesheets.

XmlReader

XmlReader is a high-performance class for reading an XML stream in a low-level, forward-only manner.

Consider the following XML file, customer.xml:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<customer id="123" status="archived">
  <firstname>Jim</firstname>
  <lastname>Bo</lastname>
</customer>

To instantiate an XmlReader, you call the static XmlReader.Create method, passing in a Stream, a TextReader, or a URI string:

using XmlReader reader = XmlReader.Create ("customer.xml");
  ...

Note

Because XmlReader lets you read from potentially slow sources (Streams and URIs), it offers asynchronous versions of most of its methods so that you can easily write nonblocking code. We cover asynchrony in detail in Chapter 14.

To construct an XmlReader that reads from a string:

using XmlReader reader = XmlReader.Create (
  new System.IO.StringReader (myString));

You can also pass in an XmlReaderSettings object to control parsing and validation options. The following three properties on XmlReaderSettings are particularly useful for skipping over superfluous content:

bool IgnoreComments // Skip over ...