=== Library System Project ===
CSS502 Assignment #3
Winter 2013
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A regional library, Safely Housing Hallowed Hardcopies (SHHH), wishes to automate the process of tracking books. This task is simplified by the fact that SHHH has only three types of books - children's books, fiction, periodicals - each sorted differently as described below. SHHH wishes to be able to allow patrons to check out books, return books, and to display the contents of the library (all three categories) and display a report of a patron's history at any time. All books are displayed by category, sorted within the category. Output must be formatted for easy reading with data in columns.
Design and write a program that will
- Initialize the contents of each of the three categories of books
- Process an arbitrary sequence of check-outs, returns, and displays of different kinds of information
Notes
- Books (except periodicals) have title, author, and date. The library stores
- Children's books sorted by title, then by author
- Fiction books sorted by author, then by title
- Periodicals sorted by date (year, then month), then by title
Assume each piece of data is uniquely identified by its sorting criteria (other information not used when sorting or retrieving). A data file is used for the initialization. One line in the file contains information on one item. To facilitate processing, children's books are marked with a 'Y' (for youth), fiction is marked with an 'F', and periodicals are marked with a 'P'. The first character of each line indicates this book type. After the type is author, then title, and date (year, int). Note that periodicals do not have an author and that the date will include month and year (both ints). Author and title are comma terminated. For example,

F Pirsig Robert, Zen & the Art of Motorcycle Maint, 1974
P Communications of the ACM, 3 2001
P Communications of the ACM, 12 1998
Z Blah blah of the ACM, 12 9999
Y Seuss Dr., Yertle the Turtle, 1950
Y Williams Jay, Danny Dunn & the Homework Machine, 1959

You can assume the format is correct, but codes may be invalid; e.g., the 'Z' code says the line of data is not valid. The library owns five copies of each item in the data file except periodicals where it only owns one copy. While the data for an item is minimal, do not assume (i.e., design and implement) that is the case. Design and implement as though there may be much more data for an item. Everything, including the output, could vary greatly if there was more data. Your design and implementation should work for any amount of information. 
- Library patron information will also be found in a data file, one line per patron. Sample data includes a unique 4-digit unique ID number, last name, first name. A blank separates fields. For example:

1234 Mouse Mickey

You can assume correctly formatted data. The assumption about more information applies also to a patron.
- While normally you would expect a program like this to be interactive, to test your program, another data file is used. It contains an arbitrary sequence of commands, one per line. The first char of each line ('C' for checkout, 'R' for return, 'H' to display a patron's history) indicates the action for a patron, or 'D' for library display of the three categories of books, sorted within the category. When it is a patron command, after the character key ('C', 'R', 'H'), there will be a blank, then the patron ID, then the character book type ('F, 'P', 'Y'), then the book format (currently only 'H' for hard copy ), and then the book data (based on the sorting criteria from above). Commas terminate in the same place as in the book data file. For example:

C 1234 F H Walker Alice, The Color Purple,
C 1234 P H 1996 3 Communications of the ACM,
D
H 1234
R 1234 F H Walker Alice, The Color Purple,
X 5678 Y Z Yertle the Turtle, Seuss Dr.,
R 5678 Z H Yertle the Turtle, Seuss Dr.,
R 9999 Y H Blah Blah Blah, Blah Blah,

The data is correctly formatted, but you must handle an invalid action code, an incorrect patron ID (not found), invalid format code, and invalid book (not found). For example, the 'X' is an invalid action code; 9999 is not a valid patron ID (not a data item from the patron data file); 'Z' is an invalid format type; the 'Y' is an invalid book code; and there is no youth book with tile "Blah Blah Blah" . For bad data, get (read from the data file) and ignore the rest of the line of data.
- You must handle errors, any invalid data as stated above: incorrect codes, invalid book or patron, and incorrect commands (a return command when a book was not checked out). Display error messages, but do NOT display anything when a successful command is performed.
- When printing, conserve paper. Use one line per item (some information may be truncated). Displays are to be nicely formatted, in easily read columns, printed in portrait mode without wrapping. For a show of library contents, show each book category (all data for that type) with how many hard copies are checked out and how many remain. For a display of patron history, show a list of whether an item is currently checked out or not. Show a list of every command in the order they occur and specify whether checked out or returned.
- A requirement of this assignment is that you use at least one hash table. Note that in the design you do not include details of hash functions and hash tables. To remind you about hashing: A hash function maps a value to an element in an array, the hash table. If it is a unique mapping, there is no need for searching so an insert or look-up is a O(1) operation. If it is not a unique mapping, the collision must be handled, but it is still efficient. Two simple unique mapping examples help you understand hashing and hash tables:
(1) Suppose you're writing game software where a user needs to guess a letter and you need to keep track of the letters already guessed and those not guessed (e.g., Wheel of Fortune). You can easily map the letters of the alphabet to subscripts of an array ranging from zero to 25. You've checked for a valid letter and made sure it's lowercase. Then the hash function, h(letter), takes a letter and returns the subscript by computing letter-'a' (ascii value of letter minus ascii value of 'a'). So, 'a' maps to 0, 'b' to 1, 'c' to 2, 'd' to 3, and so on.
Call the value, letter-'a', returned by the function, subscript. Then, you are examining hashTable[subscript] which gets you to the bool value for the letter you're looking up. Traversing the array is not needed.
(2) Suppose I created an array to hold information about 502 students. I can use your ID number as a subscript into the array to find your information. Students are not contiguously sorted in any manner, but I can quickly do a look-up given your ID number. The array element table[IDnumber] is your information. Note that there is wasted memory, but some arithmetic calculations to reduce the wasted memory could be done if desired.
- A requirement of this assignment is to use inheritance. In general, avoid templates for your primary data structures. If you find you're using templates a lot, run it by me, as this assignment is designed for you to practice using inheritance. There are no other specific requirements for this assignment, but as always it should be well designed (not violate the basic design principles), easily extensible, efficiently coded, well documented, etc.