How to remove element(s) from std::vector without resizing it

Question

iterator erase ( iterator position );

iterator erase ( iterator first, iterator last );

Erase elements Removes from the vector container either a single element (position) or a range of elements ([first,last)).

This effectively reduces the vector size by the number of elements removed, calling each element's destructor before.

and:

remove

Removes all elements equaling the given value value from the range, defined by [first, last). Removing is done by shifting the elements in the range in such a way that required elements are overwritten. The elements between the old and the new ends of the range are left intact. Iterator to the new end of the range is returned.

Is there any way to remove elements from a std::vector within an iterator range(something like remove, but ALL elements from [first, last]) without resizing the vector? I need to keep it's maximum size that it reached at runtime to prevent reallocs.

Thanks!

Answer 1

resize will never reduce the capacity of the vector - you can safely use erase for this.

Use reserve to make a vector preallocate space for a certain number of items. Unless you actually exceed this limit, no insert or erase or resize will lead to a realloc. If you exceed it, the vector will internally reserve more space - but it will not reduce the internal capacity.