dv writes:

Hello,

I need to find out the size of a range defined by two ordered_non_unique iterators . Right now I just use std::distance() for this, however, the time complexity in this case is O(n). Is there some special way for calculating distances between multi-index container iterators?

No, I'm afraid there's no other option but to use std::distance and this is O(n). If this particular operation is of special relevance to you you can consider replacing your ordered_index with a random_access index and keep this sorted manually (basically by choosing the point of insertion with std::lower_bound): in this scenario, getting the distance between iterators is constant time. HTH, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo