<?xml version="1.0" encoding="utf-8" ?>
<pets><cat color="black" weight="10"><price>100</price><desc>this is a black cat</desc></cat><cat color="white" weight="9"><price>80</price><desc>this is a white cat</desc></cat><cat color="yellow" weight="15"><price>80</price><desc>this is a yellow cat</desc></cat><dog color="black" weight="10"><price>100</price><desc>this is a black dog</desc></dog><dog color="white" weight="9"><price>80</price><desc>this is a white dog</desc></dog><dog color="yellow" weight="15"><price>80</price><desc>this is a yellow dog</desc></dog>
</pets>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml.XPath;
using System.Xml;namespace UseXPathDotNet
{class Program{static void Main(string[] args){UseXPathWithXPathDocument();UseXPathWithXmlDocument();Console.Read();}static void UseXPathWithXmlDocument(){XmlDocument doc = new XmlDocument();doc.Load("http://www.cnblogs.com/yukaizhao/rss");//使用xPath选择需要的节点XmlNodeList nodes = doc.SelectNodes("/rss/channel/item[position()<=10]");foreach (XmlNode item in nodes){string title = item.SelectSingleNode("title").InnerText;string url = item.SelectSingleNode("link").InnerText;Console.WriteLine("{0} = {1}", title, url);}}static void UseXPathWithXPathDocument(){XPathDocument doc = new XPathDocument("http://www.cnblogs.com/yukaizhao/rss");XPathNavigator xPathNav = doc.CreateNavigator();//使用xPath取rss中最新的10条随笔XPathNodeIterator nodeIterator = xPathNav.Select("/rss/channel/item[position()<=10]");while (nodeIterator.MoveNext()){XPathNavigator itemNav = nodeIterator.Current;string title = itemNav.SelectSingleNode("title").Value;string url = itemNav.SelectSingleNode("link").Value;Console.WriteLine("{0} = {1}",title,url);}}}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Xml;namespace UseXPath1
{class Program{static void Main(string[] args){string xml = @"<?xml version=""1.0"" encoding=""utf-8"" ?>
<pets><cat color=""black"" weight=""10"" count=""4""><price>100</price><desc>this is a black cat</desc></cat><cat color=""white"" weight=""9"" count=""5""><price>80</price><desc>this is a white cat</desc></cat><cat color=""yellow"" weight=""15"" count=""1""><price>110</price><desc>this is a yellow cat</desc></cat><dog color=""black"" weight=""10"" count=""7""><price>114</price><desc>this is a black dog</desc></dog><dog color=""white"" weight=""9"" count=""4""><price>80</price><desc>this is a white dog</desc></dog><dog color=""yellow"" weight=""15"" count=""15""><price>80</price><desc>this is a yellow dog</desc></dog><pig color=""white"" weight=""100"" count=""2""><price>8000</price><desc>this is a white pig</desc>   </pig>
</pets>";using (StringReader rdr = new StringReader(xml)){XmlDocument doc = new XmlDocument();doc.Load(rdr);//取所有pets节点下的dog字节点XmlNodeList nodeListAllDog = doc.SelectNodes("/pets/dog");//所有的price节点XmlNodeList allPriceNodes = doc.SelectNodes("//price");//取最后一个price节点XmlNode lastPriceNode = doc.SelectSingleNode("//price[last()]");//用双点号取price节点的父节点XmlNode lastPriceParentNode = lastPriceNode.SelectSingleNode("..");//选择weight*count=40的所有动物，使用通配符*XmlNodeList nodeList = doc.SelectNodes("/pets/*[@weight*@count=40]");//选择除了pig之外的所有动物,使用name()函数返回节点名字XmlNodeList animalsExceptPigNodes = doc.SelectNodes("/pets/*[name() != 'pig']");//选择价格大于100而不是pig的动物XmlNodeList priceGreaterThan100s = doc.SelectNodes("/pets/*[price div @weight >10 and name() != 'pig']");foreach (XmlNode item in priceGreaterThan100s){Console.WriteLine(item.OuterXml);}//选择第二个dog节点XmlNode theSecondDogNode = doc.SelectSingleNode("//dog[position() = 2]");//使用xpath ，axes 的 parent 取父节点XmlNode parentNode = theSecondDogNode.SelectSingleNode("parent::*");//使用xPath选择第二个dog节点前面的所有dog节点XmlNodeList dogPresibling = theSecondDogNode.SelectNodes("preceding::dog");//取文档的所有子孙节点priceXmlNodeList childrenNodes = doc.SelectNodes("descendant::price");}Console.Read();}}
}