csharp_tutorial_5.cs

static List<AdDetails> GetAdDetails(List<string> urls, string Keyword){
     var lstAdDetails = new List<AdDetails>();

     foreach (var url in urls){
         var htmlNode = GetHtml(url);
         var AdDetails = new AdDetails();

         AdDetails.AdTitle = htmlNode.OwnerDocument.DocumentNode.SelectSingleNode("//html/head/title").InnerText;
         var description = htmlNode.OwnerDocument.DocumentNode.SelectSingleNode("//html/body/section/section/section/section").InnerText;
         AdDetails.AdDescription = description.Replace("\n        \n            QR Code Link to This Post\n            \n        \n", "");
         AdDetails.AdUrl = url;

         var KeywordInTitle = AdDetails.AdTitle.ToLower().Contains(Keyword.ToLower());
         var KeywordInDescription = AdDetails.AdDescription.ToLower().Contains(Keyword.ToLower());

         if(KeywordInTitle || KeywordInDescription){
             lstAdDetails.Add(AdDetails);

         }

     }
     return lstAdDetails;
 }