How do I use a custom comparer with the Linq Distinct method?

Question

I was reading a book about Linq, and saw that the Distinct method has an overload that takes a comparer. This would be a good solution to a problem I have where I want to ge

Answer 1

You're implementing your comparer as an IComparer, the LINQ method overload requires an implementation of IEqualityComparer:

private class GribulatorComparer : IEqualityComparer {
  public bool Equals(Gribulator g1, Gribulator g2) {
    return g1.ID == g2.ID;
  }
}

edit:

For clarification, the IComparer interface can be used for sorting, as that's basically what the Compare() method does.

Like this:

items.OrderBy(x => new ItemComparer());

private class ItemComparer : IComparer
{
    public int Compare(Item x, Item y)
    {
        return x.Id.CompareTo(y.Id)
    }
}

Which will sort your collection using that comparer, however LINQ provides a way to do that for simple fields (like an int Id).

items.OrderBy(x => x.Id);