There are many variations of linked lists. We can make the list into a circular list, or ring, by changing the
link of the last record from zero to the address of the first record in the list. Now we can reach every
item in the list starting at any item in the list. Figure H-7(a) shows a circular list for the StudentNumber
order. A two-way linked list has links in both directions. In Figure H-7(b), a two-way linked list has been
created for both ascending and descending student orders.
Records ordered using linked lists cannot be stored on a sequential file because some type of directaccess
file organization is needed to use the link values. Thus, either indexed sequential or direct file
organization is required for linked-list processing.