Demerits of circular linked list over linear linked list

Question

Write down the demerits of circular linked list over linear linked list?

Answer 1

First, the assumption is that the question is certainly about circular vs. linear lists, as opposed to uni-directional vs bi-directional lists.

A linear list is one that holds no valid, however in fact a designated invalid; value for the reference to the last item's successor, and first item's predecessor. The name for this invalid reference value is subject to the execution language, typically NULL, nil or nul.

A circular list only employs valid reference values. Two forms of rings exist: the closed ring and the sentinel ring.
The closed is one where the last item's successor references first item, and first item's predecessor dereferences the last item.

A characteristic of closed rings is that the algorithm can’t normally stop iterating on an "end reached" criterion. There will be dissimilar criteria, subject to the algorithm. A closed ring can never be empty; however it can go in and out of existence.

A sentinel ring is one that holds one artificial element, the sentinel. This item acts as the anchor, as the last item's successor, and first item's predecessor. A sentinel ring has the well-stated start and stop (whenever iteration reaches the sentinel). The sentinel is an empty ring's only element. The reliable existence of the sentinel rids the ring of any invalid references; a useful facet in the design of robust software.