Question

I have 2 different lists:

public class Foo
{
    public Int32 Id { get; set; }
}

ICollection<Foo> OriginalCollection
ICollection<Foo> NewCollection

I want to generate 2 lists to be able to foreach them…

• All items that OriginalCollection contains that NewCollection does not (basically, a collection of stuff that was removed).
• All items that OriginalCollection does not contain that NewCollection does (basically, a collection of stuff that was added).

I know I’ll get back an IEnumerable with LINQ, that’s fine since I need to foreach. I just have no idea what my queries should look like…

---

Update:

I forgot to mention that I did try the Except clause… it failed because the objects are not the same. They only contain the same Id.

Answer 1

So, you want the Complement of the Set.
This post seems to fit your needs:

Quickest way to find the complement of two collections in C#

Or perhaps the Enumerable.Except method:

http://msdn.microsoft.com/en-us/library/system.linq.enumerable.except.aspx