On 31 October 2013 16:10, Klaim - Joël Lamotte <mjklaim@gmail.com> wrote:

What would "valid"/"invalid" means here?

If it's "exist" or "don't exist", then maybe using boost::optional<MyPod> would be enough.

That's right. How about sizeof( boost::optional<MyPod> ) vs sizeof( MyPOD ) ?

Also, what sort of iterator can iterate over just the valid values? or how to implement one?

The point here is that there's a small number of elements that are invalid, their indices in the container are random,