XPathNavigator.Evaluate (String, IXmlNamespaceResolver)
Imports System Imports System.Xml Imports System.Xml.XPath Public Class MainClass Public Shared Sub Main() Dim document As XPathDocument = New XPathDocument("domainBooks.xml") Dim navigator As XPathNavigator = document.CreateNavigator() Dim manager As XmlNamespaceManager = New XmlNamespaceManager(navigator.NameTable) manager.AddNamespace("bk", "http://www.domain.com/books") Dim total As Double = CType(navigator.Evaluate("sum(descendant::bk:book/bk:price)", manager), Double) Console.WriteLine("Total price for all books: {0}", total.ToString()) End Sub End Class