C++0x is introducing unordered_set
, which is available in boost
and many other places. What I understand is that unordered_set
is hash table with O(1)
lookup complexity. On the other hand, set
is nothing but a tree with log(n)
lookup complexity.
Why on earth would anyone use set
instead of unordered_set
? I.e., is there a need for set
anymore?
When, for someone who wants to iterate over the items of the set, the order matters.