֪һXMLļbookstore.xml£
<?xml version="1.0" encoding="gb2312"?>
<bookstore>
  <book genre="fantasy" ISBN="2-3631-4">
    <title>Oberon's Legacy</title>
    <author>Corets, Eva</author>
    <price>5.95</price>
  </book>
</bookstore>
 
1<bookstore>ڵвһ<book>ڵ㣺
   XmlDocument xmlDoc=new XmlDocument();
   xmlDoc.Load("bookstore.xml");
   XmlNode root=xmlDoc.SelectSingleNode("bookstore");//<bookstore>
   XmlElement xe1=xmlDoc.CreateElement("book");//һ<book>ڵ
   xe1.SetAttribute("genre","޺");//øýڵgenre
   xe1.SetAttribute("ISBN","2-3631-4");//øýڵISBN
 
   XmlElement xesub1=xmlDoc.CreateElement("title");
   xesub1.InnerText="CSŵͨ";//ıڵ
   xe1.AppendChild(xesub1);//ӵ<book>ڵ
   XmlElement xesub2=xmlDoc.CreateElement("author");
   xesub2.InnerText="";
   xe1.AppendChild(xesub2);
   XmlElement xesub3=xmlDoc.CreateElement("price");
   xesub3.InnerText="58.3";
   xe1.AppendChild(xesub3);
 
   root.AppendChild(xe1);//ӵ<bookstore>ڵ
   xmlDoc.Save("bookstore.xml");
//===============================================
Ϊ
<?xml version="1.0" encoding="gb2312"?>
<bookstore>
  <book genre="fantasy" ISBN="2-3631-4">
    <title>Oberon's Legacy</title>
    <author>Corets, Eva</author>
    <price>5.95</price>
  </book>
  <book genre="޺" ISBN="2-3631-4">
    <title>CSŵͨ</title>
    <author></author>
    <price>58.3</price>
  </book>
</bookstore>
 
2޸Ľڵ㣺genreֵΪ޺조ĽڵgenreֵΪupdate޺족ýڵӽڵ<author>ı޸Ϊʤ
    XmlNodeList nodeList=xmlDoc.SelectSingleNode("bookstore").ChildNodes;//ȡbookstoreڵӽڵ
   foreach(XmlNode xn in nodeList)//ӽڵ
   {
    XmlElement xe=(XmlElement)xn;//ӽڵתΪXmlElement
    if(xe.GetAttribute("genre")=="޺")//genreֵΪ޺족
    {
     xe.SetAttribute("genre","update޺");//޸ĸΪupdate޺족
 
     XmlNodeList nls=xe.ChildNodes;//ȡxeӽڵӽڵ
     foreach(XmlNode xn1 in nls)//
     {
      XmlElement xe2=(XmlElement)xn1;//ת
      if(xe2.Name=="author")//ҵ
      {
       xe2.InnerText="ʤ";//޸
       break;//ҵ˳Ϳ
      }
     }
     break;
    }
   }
 
   xmlDoc.Save("bookstore.xml");//档
//==================================================
Ϊ
<?xml version="1.0" encoding="gb2312"?>
<bookstore>
  <book genre="fantasy" ISBN="2-3631-4">
    <title>Oberon's Legacy</title>
    <author>Corets, Eva</author>
    <price>5.95</price>
  </book>
  <book genre="update޺" ISBN="2-3631-4">
    <title>CSŵͨ</title>
    <author>ʤ</author>
    <price>58.3</price>
  </book>
</bookstore>
 
3ɾ <book genre="fantasy" ISBN="2-3631-4">ڵgenreԣɾ <book genre="update޺" ISBN="2-3631-4">ڵ㡣
XmlNodeList xnl=xmlDoc.SelectSingleNode("bookstore").ChildNodes;
 
   foreach(XmlNode xn in xnl)
   {
    XmlElement xe=(XmlElement)xn;
    if(xe.GetAttribute("genre")=="fantasy")
    {
     xe.RemoveAttribute("genre");//ɾgenre
    }
    else if(xe.GetAttribute("genre")=="update޺")
    {
     xe.RemoveAll();//ɾýڵȫ
    }
   }
   xmlDoc.Save("bookstore.xml");
//===========================================
Ϊ
<?xml version="1.0" encoding="gb2312"?>
<bookstore>
  <book ISBN="2-3631-4">
    <title>Oberon's Legacy</title>
    <author>Corets, Eva</author>
    <price>5.95</price>
  </book>
  <book>
  </book>
</bookstore>
 
4ʾݡ
   XmlNode xn=xmlDoc.SelectSingleNode("bookstore");
 
   XmlNodeList xnl=xn.ChildNodes;
   
   foreach(XmlNode xnf in xnl)
   {
    XmlElement xe=(XmlElement)xnf;
    Console.WriteLine(xe.GetAttribute("genre"));//ʾֵ
    Console.WriteLine(xe.GetAttribute("ISBN"));
 
    XmlNodeList xnf1=xe.ChildNodes;
    foreach(XmlNode xn2 in xnf1)
    {
     Console.WriteLine(xn2.InnerText);//ʾӽڵı
    }
   } 
