Reversing or reverse iterating an unordered_map

Question

I'm trying to print the contents of an unordered_map in reverse order, but it doesn't have rbegin or rend, so you can't use reverse_iterator. How is reversing of the unordered_map supposed to be done?

EDIT (from comment): I want the keys to be in the order they were inserted in, hence I cant use map. The keys appear to stay in the insertion order, but I need them reversed.

Answer 1

Just reading the first sentence in your question gives you the answer:

I'm trying to print the contents of an unordered_map in reverse order

You cannot print in any order because, well, it is unordered. It makes no sense talking about order in an unordered structure. It does not matter how the contents of an unordered_map are organised internally: this is an implementation detail and you cannot access it. To the outside world, an unordered_map exhibits no order at all and you cannot expect it to do it.

Answer 2

You can cobble up your own pair of reverse iterators from any pair of bidirectional iterators:

std::reverse_iterator rbegin(first);
std::reverse_iterator rend(last);

As @Tin suggested, this doesn't work. Never mind.