On Wed, 16 Mar 2022 at 12:24, Nevin Liber <nevin@cplusplusguy.com> wrote:

My opinion is that it should have one, and if it does, the expectation is that it is unordered.

For most containers (other than string), I rarely use its comparison operators, but when I need them, they are very handy.

We are supposed to be designing a coherent standard library, and all the containers in the standard library are equality comparable. This should not be a snowflake.

How does the complexity compare with the complexity of unordered_multiset::operator==?

My apologies to Henry Miller from earlier, time complexity would be approx O(n log n), as he states - I forgot the time complexity of the sort function itself. At any rate, 1 x O(n) (gather pointers), 1 x O(n log n) (sort pointers), 1 x O(n) (compare elements via pointers).

There may be better ways of doing what I'm talking about, this is only what I've managed to come up with thus far.

Whereas unordered_multiset::operator==is O(n pow 2) in worst case.