Prevent direct access to std::map keys

Question

I would like to wrap a std::map so the client is unaware that I am storing their positive integer keys actually as negative integers. I need to allow iterating

Answer 1

do 
{
    std::cout << "key: " << key << " val: " << value << std::endl;
}while (o.getNextElement(key, value));

So all operations are within the loop like this.