What does the length() function return in a linked list?

• A. It returns the count of nodes
• B. It returns the sum of node values
• C. It returns the index of the last node
• D. It returns the memory size of the list

Answer: (A)

Length reflects how many nodes are in the list. The length() function returns that count—the number of elements in the list, not the data values stored in them. It is not the index of the last node, since indices are a separate concept and many linked lists don’t track indices by default. It also isn’t the memory size of the list; memory usage depends on how many nodes exist and how much space each node’s structure consumes, which is independent of the count you get from length().

In practice, you can implement this with a counter that is updated on insertions and deletions (giving length() in constant time), or compute it by traversing from the head to the end and tallying nodes (which takes linear time). If the list has three nodes, length() would return 3.