# 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 `push` or `try_pop` operations.

## size

>     size_type size() const;

> Returns: the number of elements in the container.

> The result may differ from the actual number of elements in case of pending concurrent `push` or `try_pop` operations.