using System;

using System.Xml.Linq;

​

public class Program

{

    public static void Main(string[] args)

    {

        const string xml = @"<location>

    <city>Denver</city>

    <state>CO</state>

    <country>United States</country>

</location>";

​

        var doc = XDocument.Parse(xml);

​

        doc.Root.Element("city").Value = "London";

        doc.Root.Element("state").Value = "Some value with & <> in";

        doc.Root.Element("country").ReplaceNodes(new XCData("Some CDATA content with & <>"));

​

        Console.WriteLine(doc);

    }

}

​

​