C++ fastest way to clear or erase a vector

Question

I have a code where I routinely fill a vector with between 0 and 5000 elements. I know the maximum never exceeds 5000. Instead of initializing vector multiple times, I would

Answer 1

Anything you do to remove the existing items from the vector needs to (potentially) invoke the destructor of each item being destroyed. Therefore, from the container's viewpoint, the best you can hope for is linear complexity.

That leaves only the question of what sort of items you store in the vector. If you store something like int that the compiler can/will know ahead of time has no destructor to invoke, chances are at least pretty good that removal will end up with constant complexity.

I doubt, however, that changing the syntax (e.g., clear() vs. resize() vs. erase(begin(), end()) ) will make any significant difference at all. The syntax doesn't change that fact that (in the absence of threading) invoking N destructors is an O(N) operation.