title: Create hash map with parameters ordered in the way inserted
body: <p>I want to change the std::map (it's hash function) so when iterated to return pairs in the way they are inserted. I have tried with unordered map, but with no success. So I guess I have to create a hash function that is incrementing and returns bigger value every time. How can I do that? I'm not working with big data, so performance is not a problem.</p>