What is the difference between begin() and end() methods?

• A. begin returns an iterator to the start; end returns an iterator past the last node.
• B. begin returns null; end returns the last node.
• C. begin returns last; end returns first.
• D. begin returns size; end returns capacity.

Answer: (A)

The key idea is how iteration ranges are defined. begin gives you an iterator to the first element, while end gives you an iterator that sits one step past the last element. This half-open range [begin, end) makes loops simple and consistent: you advance the iterator until you reach end, and you’ve visited every element exactly once. In a linked list, begin would point to the head node, and end is typically a special past-the-tail marker (often a null or sentinel) that you should not dereference. If the list is empty, begin and end are equal, so the loop doesn’t run at all.

Other interpretations don’t fit because dereferencing end isn’t valid, and end isn’t meant to point to the last element or to a size or capacity value. Those are different concepts; iterators and their end marker are about traversing the elements safely.