void reserve( size_type size );
Sets the capacity of the container to at least
size. New storage is allocated if necessary.
size is greater than
capacity(), all iterators and references, including the past-the-end iterator, are invalidated. Otherwise, no iterators or references are invalidated.
|size||-||new capacity of the container|
 Return value
std::length_error if size > max_size().
Linear in the size of the container
 See also
| returns the number of elements that can be held in currently allocated storage |
(public member function)