C# 操作XML

<?xml version="1.0" encoding="UTF-8"?>
<Users>
  <User>
    <UserName>admin1</UserName>
    <PassWord>1234567</PassWord>
  </User>
</Users>

 class Program 
    {
        static void Main(string[] args)
        {
            XmlElement theUser = null, root = null;
            XmlDocument xmldoc = new XmlDocument();
            try
            {
                xmldoc.Load("Users.xml");
                root = xmldoc.DocumentElement;

                theUser = (XmlElement)root.SelectSingleNode("/Users/User");
                Console.WriteLine("---  查找密码 ----");
                Console.Out.WriteLine(theUser.GetElementsByTagName("UserName").Item(0).InnerText);
                Console.WriteLine("---  修改密码 ----");
                theUser.GetElementsByTagName("UserName").Item(0).InnerText = "admin2";
                Console.WriteLine(theUser.GetElementsByTagName("UserName").Item(0).InnerText);
                xmldoc.Save("Users.xml");
            }
            catch (Exception e)
            {
                Console.Out.WriteLine(e.Message);
            }
            Console.ReadKey();
       
        }

using System.Xml;