c# - Filter XDocument more efficiently -

i filter high performance xml elements xml document.

take instance xml file contacts:

<?xml version="1.0" encoding="iso-8859-1"?> <?xml-stylesheet type="text/xsl" href="asistentes.xslt"?> <contactlist evento="cena navidad 2010" empresa="company">   <contact type="1" id="1">     <name>name1</name>     <email>xxxx@zzzz.es</email>     <confirmado>si</confirmado>   </contact>   <contact type="1" id="2">     <name>name2</name>     <email>xxxxxxxxx@zzzze.es</email>     <confirmado>sin confirmar</confirmado>   </contact> </contaclist> 

my current code filter xml document:

using system;  using system.xml.linq;   class test  {     static void main()     {        string xml = @" xml above";        xdocument doc = xdocument.parse(xml);         foreach (xelement element in doc.descendants("contact")) {          console.writeline(element);          var id = element.attribute("id").value;          var valor = element.descendants("confirmado").tolist()[0].value;          var email = element.descendants("email").tolist()[0].value;          var name = element.descendants("name").tolist()[0].value;          if (valor.tostring() == "si") { }       }    }  }  

what best way optimize code filter on <confirmado> element content?

var doc = xdocument.parse(xml);   var query = contact in doc.root.elements("contact")             let confirmado = (string)contact.element("confirmado")             confirmado == "si"             select new             {                 id    = (int)contact.attribute("id"),                 name  = (string)contact.element("name"),                 email = (string)contact.element("email"),                 valor = confirmado             };  foreach (var contact in query) {     ... } 

points of interest:

• doc.root.elements("contact") selects <contact> elements in document root, instead of searching whole document <contact> elements.

• the xelement.element method returns first child element given name. no need convert child elements list , take first element.

• the xelement , xattribute classes provide wide selection of convenient conversion operators.