Does resizing () reduce the reservation made by an earlier reservation () to a smaller size?

Question

So, if I reserve (100) first, add some elements and then resize (0) (or any other number smaller than the current size), will the vector reallocate memory to less space than 100 elements?

Answer 1

vector<T>::resize(0) should not cause a reallocation or deletion of allocated memory, and for this reason, in most cases, vector<T>::clear() preferable.

See the answers to this question for more details: std :: vector resize down

Answer 2

Running vector::resize(0) or a smaller count, not the current count, should not free memory. However, it can destroy these elements.

For reference on std::vector::resize , see std :: vector :: resize