Swapping keys and values of a map in C++

Question

I'm looking for a function in C++ that for swap the contents of a map ... that is: those that were the keys now become the items and those that the items were now the keys. Can you tell me if there is something about this?

Answer 1

As Geoffroy said, std::map doesn't allow this behaviour. However, you might want to use a STL-like container Boost.Bimap - bidirectorial map.

A Bimap is a data structure that represents bidirectional relations between elements of two collections. The container is designed to work as two opposed STL maps. A bimap between a collection X and a collection Y can be viewed as a map from X to Y (this view will be called the left map view) or as a map from Y to X (known as the right map view).