Size and capacity

empty

bool empty() const;

Returns: true if the container is empty; false, otherwise.

The result may differ from the actual container state in case of pending concurrent insertions.

size

size_type size() const;

Returns: the number of elements in the container.

The result may differ from the actual container size in case of pending concurrent insertions.

max_size

size_type max_size() const;

Returns: the maximum number of elements that container can hold.