title: Compare two diferrent lists to Populate a third list
body: <p>I have two lists of diferrent types which has a common guid i need to compare on .</p>
  
  <p>if the value exists in both of the lists I need to populate an isPresent property in a third list.</p>
  
  <pre><code> class a {
   Guid stub;
   string name;
   int number;
   }
  
   class b {
   Guid SecondStub;
   .
   .
  
   }
   class temp 
   {
    bool isPresent;
    string somethingElse;
   }
  
   ------------------------------------------
  </code></pre>
  
  <p>now I have one List each of type a and b and I need to populate an isPresent property in a third List.</p>
  
  <pre><code> foreach (var a in ListofA)
   {
   temp.Add(new Temp(){ 
   isPresent = ListOfB.Where(l =&gt; l.SecondStub == a.Stub).Equals(null)
   })};
  </code></pre>
  
  <p>is not working .. please help.</p>