What does the empty() method return?

• A. It returns true if the count of nodes is 0.
• B. It returns true if the list has elements.
• C. It returns true if the list is full.
• D. It returns the number of elements.

Answer: (A)

The main idea is a quick check of whether the structure has any elements. empty() returns a boolean indicating emptiness: it is true when there are no nodes, i.e., the count of nodes is 0. If there’s at least one node, the list isn’t empty and the method returns false. For linked lists there isn’t a notion of being “full,” since they grow as needed, so empty() isn’t about fullness. It also isn’t meant to return a number. So the correct interpretation is that it returns true when the number of nodes is zero. For example, an newly created list would report empty() as true, and after adding an element, empty() would be false.