How can i estimate memory usage of std::map?

Question

For example, I have a std::map with known sizeof(A) and sizeof(B), while map has N entries inside. How would you estimate its memory usage? I\'d say it\'s something like

Answer 1

The size of the map really depends on the implementation of the map. You might have different sizes on different compilers/platforms, depending on which STL implementation they are providing.

Why do you need this size?