C#导航器Xpath与XPathNavigator类

XPathDocument doc = new XPathDocument("./books.xml");
XPathNavigator nav = ((IXPathNavigable)doc).CreateNavigator();

XmlDocument doc = new XmlDocument(); 
doc.Load("./books.xml"); 
XPathNavigator nav2 = doc.CreateNavigator();

//查询bookstore的子元素book中genre属性值为novel的所有节点
XPathNodeIterator iter = nav.Select("/bookstore/book[@genre='novel']");
while (iter.MoveNext())
{
    //迭代所有子代节点
    XPathNodeIterator newIter = iter.Current.SelectDescendants(XPathNodeType.Element, false);
    while (newIter.MoveNext())
    {
        Console.WriteLine(newIter.Current.Name+ " : " +newIter.Current.Value);
    }
}

//统计图书总价   
Console.WriteLine("Total price = {0}", nav.Evaluate("sum(bookstore/book/price)"));

XmlDocument doc = new XmlDocument();
doc.Load("./books.xml");
XPathNavigator nav2 = doc.CreateNavigator();
//判断是否可编辑
if (nav2.CanEdit)
{
    XPathNodeIterator iter = nav2.Select("bookstore/book/price");
    while (iter.MoveNext())
    {
        //在当前节点之后插入新节点
        iter.Current.InsertAfter("5");
    }
}
doc.Save("./newBooks.xml");

//读：
XmlReader reader=nav.ReadSubtree();
while(reader.Read())
{
   Console.Write(reader.ReadOuterXml());
}

//写：
XmlWriter writer=XmlWriter.Create("./1.xml");
nav.WriteSubtree(writer);
writer.Close();