C++ Case Study.

 This case study is a program that can be used in a small library to include new books in the library, to check out books to people, and to return them. As this program is a practice in the use of linked lists, almost everything is implemented in terms of such lists. But to make the program more interesting, it uses linked lists of linked lists that also contain cross-references (see Figure 3.26). First, there could be a list including all authors of all books in the library. However, searching through such a list can be time-consuming, so the search can be sped up by choosing at least one of the two following strategies: ■ The list can be ordered alphabetically, and the search can be interrupted if we find the name, if we encounter an author’s name greater than the one we are searching for, or if we reach the end of list. ■ We can use an array of pointers to the author structures indexed with letters; each slot of the array points to the linked list of authors whose names start with the same letter. The best strategy is to combine both approaches. However, in this case study, only the second approach is used, and the reader is urged to amplify the program by adding the first approach. Note the articles a, an, and the at the beginning of the titles should be disregarded during the sorting operation. The program uses an array catalog of all the authors of the books included in the library and an array people of all the people who have used the library at least once. Both arrays are indexed with letters so that, for instance, position catalog[‘F’] refers to a linked list of all the authors whose names start with F. Because we can have several books by the same author, one of the data members of the author node refers to the list of books by this author that can be found in the library. Similarly, because each patron can check out several books, the node corresponding to this patron contains a reference to the list of books currently checked out by this patron. This fact is also indicated by setting the patron member of the checked-out book to the node pertaining to the patron who is taking the book out. Books can be returned, and that fact should be reflected by removing the appropriate nodes from the list of the checked-out books of the patron who returns them. The patron member in the node related to the book that is being returned has to be reset to null. The program defines four classes: Author, Book, Patron, and CheckedOutBook. To define different types of linked lists, the STL resources are used, in particular, the library . The program allows the user to choose one of the five operations: adding a book to the library, checking a book out, returning it, showing the current status of the library, and exiting the program. The operation is chosen after a menu is displayed and a proper number is entered. The cycle of displaying the menu and executing an elected operation ends with choosing the exit option. Here is an example of the status for a situation shown in Figure 3.26. Library has the following books: Fielding Henry * Pasquin - checked out to Chapman Carl * The History of Tom Jones Fitzgerald Edward * Selected Works * Euphranor - checked out to Brown Jim Murdoch Iris * The Red and the Green - checked out to Brown Jim * Sartre * The Bell The following people are using the library: Brown Jim has the following books * Fitzgerald Edward, Euphranor * Murdoch Iris, The Red and the Green Chapman Carl has the following books * Fielding Henry, Pasquin Kowalski Stanislaus has no books Note that the diagram in Figure 3.26 is somewhat simplified, because strings are not stored directly in structures, only pointers to strings. Hence, technically, each name and title should be shown outside structures with links leading to them. Please comment if you want the solution of this case study.