C#によるxmlファイルの読み書きのアプリケーション

<?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>

CodeXmlDocument xmlDoc=new XmlDocument();
xmlDoc.Load("bookstore.xml");
XmlNode root=xmlDoc.SelectSingleNode("bookstore");//Find <bookstore>
XmlElement xe1=xmlDoc.CreateElement("book");//Create a <book> node
xe1.SetAttribute("genre","李赞红");//set the node genre attribute
xe1.SetAttribute("ISBN","2-3631-4");//set the node's ISBN attribute
XmlElement xesub1=xmlDoc.CreateElement("title");
xesub1.InnerText="CS from Beginner to Master";//set text node
xe1.AppendChild(xesub1);//add to the <book> node
XmlElement xesub2=xmlDoc.CreateElement("author");
xesub2.InnerText="Waiting for Jie";
xe1.AppendChild(xesub2);
XmlElement xesub3=xmlDoc.CreateElement("price");
xesub3.InnerText="58.3";xe1.AppendChild(xesub3);
root.AppendChild(xe1);//add to <bookstore> node
xmlDoc.Save("bookstore.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>
<book genre="Li Zanhong" ISBN="2-3631-4">
<title>CS from Beginner to Master</title>
<author>候捷</author>
<price>58.3</price>
</book>
</bookstore>

CodeXmlNodeList nodeList=xmlDoc.SelectSingleNode("bookstore").ChildNodes;//Get all child nodes of the bookstore node
foreach(XmlNode xn in nodeList)// iterate through all child nodes
{ XmlElement xe=(XmlElement)xn;//convert child node type to XmlElement type
if(xe.GetAttribute("genre")=="李赞红")//if genre attribute value is "李赞红"
{ xe.SetAttribute("genre","update李赞红");//then change the attribute to "update李赞红"
XmlNodeList nls=xe.ChildNodes;//continue to get all child nodes of xe's child nodes
foreach(XmlNode xn1 in nls)//traverse
{XmlElement xe2=(XmlElement)xn1;//convert the type
if(xe2.Name=="author")//If found
{ xe2.InnerText="yasheng";//then modify
break;//Find the exit and you're done } } break; }}xmlDoc.Save("bookstore.xml");//Save.

<?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 Li Zanhong" ISBN="2-3631-4">
<title>CS from Beginner to Master</title>
<author>Yasheng</author>
<price>58.3</price>
</book>
</bookstore>