using System;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

using System.Globalization;

using System.Xml;

using System.Xml.Linq;                  

public class Program

{

    public static void Main()

    {

        string input = @"<tv info=""blahblah"">

  <channel id=""Channelname1"">

    <display-name lang=""en"">Channelname1</display-name>

    <icon src=""somelogo.png"" />

    <url>http://somelink.com</url>

    <channel-category>SomeValue</channel-category>

  </channel>

  <channel id=""Channelname2"">

    <display-name lang=""en"">Channelname2</display-name>

    <icon src=""somelogo.png"" />

    <url>http://somelink.com</url>

   </channel>

</tv>";

        XDocument doc = XDocument.Parse(input);

        if(doc.Descendants("channel").Any(x=>(string)x.Attribute("id") == "Channelname1" && x.Element("channel-category") != null))

        {

            Console.WriteLine("Element exist");

        }

        else Console.WriteLine("Element not exist");

    }

}