//引入命名空间
using System;
using System.IO;
using System.Xml;

public class Sample {

  public static void Main() {

    XmlDocument doc = new XmlDocument();
    doc.Load("booksort.xml");

    XmlNodeList nodeList;
    XmlNode root = doc.DocumentElement;

    nodeList=root.SelectNodes("descendant::book[author/last-name='Austen']");
 
    //Change the price on the books.
    foreach (XmlNode book in nodeList)
    {
      book.LastChild.InnerText="15.95";
    }

    Console.WriteLine("Display the modified XML document....");
    doc.Save(Console.Out);
  }
}

//引入命名空间
using System;
using System.IO;
using System.Xml;

public class Sample
{
  public static void Main()
  {

      XmlDocument doc = new XmlDocument();
      doc.Load("booksort.xml");

      //Create an XmlNamespaceManager for resolving namespaces.
      XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);
      nsmgr.AddNamespace("bk", "urn:samples");

      //Select and display the value of all the ISBN attributes.
      XmlNodeList nodeList;
      XmlElement root = doc.DocumentElement;
      nodeList = root.SelectNodes("/bookstore/book/@bk:ISBN", nsmgr);
      foreach (XmlNode isbn in nodeList){
        Console.WriteLine(isbn.Value);
      }
   }
}