[Boost-users] [MultiIndex] getting the index from set::lower_bound() iterator (or a replacement/extension)

Hi, I need a container like std::set which delivers also the index when using the member function lower_bound(). IMO std::set lacks this important functionality. I cannot use std::distance(myset.begin(), it), because that is very slow as it walks again all the items from the beginning. Can boost MultiIndex be used for this, or any other alternatives/workarounds? Here's a demonstration of what I need: struct TS { /*...*/ }; set<TS> myset; TS S(/*...*/); auto it = myset.lower_bound(S); if (it != myset.end()) { size_t ix = ...howto get the index, ie. the rank?... //... } -- Thx Uenal