std::array requires the size to be set at compile-time, while I was talking about arrays whose size is determined at construction-time. Of course std::array is also quite the useful class :-)

You can construct the vector with a given size. As long as you don’t push_back, beyond capacity, these should be o dynamic allocations.

If you want to get f cy you can also give it a custam allocator and throw an exception if you do this by mistake