How to get all subsets of an array?

Question

Given an array: [dog, cat, mouse]

what is the most elegant way to create:

[,,]
[,,mouse]
[,cat,]
[,cat,mouse]
[dog,,]
[dog,,mouse]
[dog,cat,]
[dog,cat,mouse]

I need this to work for any sized array.

This is essentially a binary counter, where array indices represent bits. This presumably lets me use some bitwise operation to count, but I can't see a nice way of translating this to array indices though.

Answer 1

Elegant? Why not Linq it.

    public static IEnumerable<IEnumerable<T>> SubSetsOf<T>(IEnumerable<T> source)
    {
        if (!source.Any())
            return Enumerable.Repeat(Enumerable.Empty<T>(), 1);

        var element = source.Take(1);

        var haveNots = SubSetsOf(source.Skip(1));
        var haves = haveNots.Select(set => element.Concat(set));

        return haves.Concat(haveNots);
    }