XmlDocument sample code for operating xml documents

<?xml version="1.0"
encoding="utf-8"?> 
<userdata createuser="false">
  <dataconnection>
   <server>xml test</server>
   <uid>sa</uid>
   <pwd>sa</pwd>
  </dataconnection>
  <net>
   <name>xml document</name>
  </net>
</userdata>

   XmlDocument doc=new
XmlDocument();
   doc.Load("config.xml");
   XmlNode
xnuser=doc.SelectSingleNode("userdata");
   string
flag=xnuser.Attributes["createuser"].InnerText;

   XmlDocument doc=new
XmlDocument();
   doc.Load("config.xml");
   XmlNode xnserver =
doc.SelectSingleNode("userdata/dataconnection/server");

   XmlDocument doc=new
XmlDocument();
   doc.Load("config.xml");
   XmlNode
xnuser=doc.SelectSingleNode("userdata");
  
xnuser.Attributes["createuser"].InnerText="false";
   doc.Save("config.xml");

XmlDocument doc = new
XmlDocument();
   XmlTextReader reader = new
XmlTextReader("config.xml");
   doc.Load("config.xml");
   XmlElement root =
doc.DocumentElement; // 获取根节点
   XmlElement tagMessage =
doc.CreateElement("net");
   XmlElement tagText =
doc.CreateElement("name");
  
tagText.InnerText  = netname;
  
tagMessage.AppendChild(tagText);  
// 追加到 xml 文本的最后面
  
root.AppendChild(tagMessage);
  
reader.Close();    
// 关闭 XmlTextReader
  
doc.Save("config.xml");    
// 保存 xml 文件