C# - How to convert List to List, when Dog is a subclass of Animal?

Question

I have a class Animal, and its subclass Dog. I have a List and I want to add the contents of some List<

Answer 1

You don't need the cast if you're using C#4:

List animals = new List();
List dogs = new List();

animals.AddRange(dogs);

That's allowed, because AddRange() accepts an IEnumerable, which is covariant.

If you don't have C#4, though, then you would have to iterate the List and cast each item, since covariance was only added then. You can accomplish this via the .Cast extension method:

animals.AddRange(dogs.Cast());

If you don't even have C#3.5, then you'll have to do the casting manually.