Modify XML existing content in C#

Question

Purpose: I plan to Create a XML file with XmlTextWriter and Modify/Update some Existing Content with XmlNode SelectSingleNode(), node.ChildNode[?].InnerText = someting, etc.

Answer 1

Using LINQ to xml if you are using framework 3.5

using System.Xml.Linq;

XDocument xmlFile = XDocument.Load("books.xml"); 
var query = from c in xmlFile.Elements("catalog").Elements("book")    
            select c; 
foreach (XElement book in query) 
{
    book.Attribute("attr1").Value = "MyNewValue";
}
xmlFile.Save("books.xml");