LINQ to Objects List Difference

Question

I have two EmailAddress generic lists, I wanted a simple way of just getting all the EmailAddress objects that are in List1 that aren\'t in List2.

I\'m thinking a le

Answer 1

Most of these answers will not work since the items in List1 and List2 may be equal in the eyes of the user, but are actually references to different instances (they are not reference equal).

Assuming Address is a string property of EmailAddress, here's a left join solution.

IEnumerable query = 
  from a1 in list1
  join a2 in list2 on a1.Address equals a2.Address into g
  from x in g.DefaultIfEmpty()
  where x == null
  select a1;