Selects the first XmlNode that matches the XPath expression.
using System; using System.IO; using System.Xml; public class Sample { public static void Main() { XmlDocument doc = new XmlDocument(); doc.Load("booksort.xml"); XmlNode book; XmlNode root = doc.DocumentElement; book=root.SelectSingleNode("descendant::book[author/last-name='A']"); book.LastChild.InnerText="15.95"; doc.Save(Console.Out); } }