CSE 143 Summer 2001 Homework 3 Due: Electronic submission by 9:30 pm, Wednesday July 25.  Paper receipt and written report due in quiz section on Thursday July 26.

Overview

For this assignment, you will be leaving the world of word processing behind to begin a new career in airline booking.  You will write a program capable of accepting departure and arrival information from the user and displaying a list of possible flights meeting those criteria.

As with all assignments, please read the instructions all the way through before beginning.  Read them once again before you turn in your assignment, to be sure you've left nothing out.

Concepts

The goal of this assignment is to gain experience with the following concepts:

• Use of dynamic data structures in classes (allocation, automatic expansion, deletion)
• Overloading Operators
• Destructors
• Copy constructors
• Assignment operators

Program Specification

This program maintains a database of airline flight information and allows the user to make queries into this database to find flights which match their desired specifications.  Each entry in the flight database contains the following elements.

• Flight number, Each flight will have a unique flight number
• Departure Location, city of departure, e.g. Seattle
• Arrival Location, city of arrival, e.g. Omaha
• Departure Time, e.g. 18:30 (NOTE: military time should be used)
• Arrival Time
• Departure Date, e..g 10/10/2001 (NOTE: The date format is XX/XX/XXXX), where X represents a numerical digit.
• Price, in dollars

The data type used  to specify the above values is ultimately up to you, however as a suggestion, using a string for all values other than the price is a good option.

When the program starts, the database is initially empty.  The program should repeatedly present the user with a menu of possible commands, then accept a command and carry it out.  This continues until the user stops the program by entering a quit command.

The available commands are indicated by a letter, which can be either upper or lower case.  The available commands are:

• r or R: Read a file
• f or F: Create a flight reservation
• c or C: Cancel flight
• q or Q: Quit

After the user enters a command letter, the command should be processed as described in the following sections.  Once the command is processed, if the command was anything other than quit, the program should request a new command and continue.

r or R: Read a file

When the user selects this option, the program should prompt for a file name and try to open that file. If it fails, it should report an error and return to the main menu.

Upon successfully opening the file, the program should read the flight information from it and merge this information into the database (more about that below). The file is composed of blocks of 7 lines each, in the following order:

Flight#
Departure Location
Arrival Location
Departure Time
Arrival Time
Departure Date
Price

There might be any number of such blocks, including none, and there is no limit on how many blocks the file may contain. The end of the input is marked by an empty line where the next Flight # would normally be, and the program should stop reading data at that point. You should assume that the input is clean. E.g. You do not need to check for errors in the input file.  An example is given below.

All flight data from the file should be “merged” into the existing database. This means:

• Flights which do not already appear in the database should be added to it.
• Flights already in the database should be updated to reflect the new information from the file.  The new information completely replaces the old information for that flight.

A flight is said to be in the database if the database already contains an entry with the same Flight#. Different flights may have the same departure or arrival location, same departure or arrival time, same departure date, or same price, but the Flight# is guaranteed to be unique.

Example File

1243A
Seattle
Omaha
09:00
11:30
09/01/2001
420.00
1488Q
San Francisco
San Jose
12:30
13:00
10/15/2001
140.99
1003B
Seattle
Omaha
18:40
21:00
09/01/2001
210.00

c or C: Cancel a flight

When the user selects this option, the program should display a list of all current flights and prompt the user to select a flight to cancel.  The selected flight should be removed from the database and its memory de-allocated.  The program should then prompt the user for another flight to cancel until -1 is entered, which should return the user to the main menu.

f or F: Create a flight reservation

When the user selects this option, the program should ask for three pieces of information from the user.

1. Departure Location
2. Arrival Location
3. Date of departure (NOTE : 0 = Any date)

The program should next use the overloaded operator== to find all flights which match those criteria from the database and display them in order of increasing price (least expensive first), preceded by a number.  An example output for Seattle --> Omaha might be:

1.     Flight Number : 1003B
        Total Price : $210.00
        
2.     Flight Number : 1243A
        Total Price : $420.00

After displaying the basic flight information, the program should request that the user select one of the flights listed by entering the number to the left of the flight.  When a flight is selected the program should then print out all pertinent information about that flight :  Number, Arrival/Departure City, Arrival/Departure Time, Departure Date, and Price. 

Redisplay the initial flight list and prompt the user for another flight.  Repeat this process until the user enters -1, at which point the program should return to the main menu.

q or Q: Quit

Exit the program. Make sure that you clean up all dynamically allocated memory before the program actually terminates. 

Implementation Requirements

The main technical goal of this assignment is to learn to use classes that have dynamically allocated data structures.  Specifically, the database of Flight information should automatically grow as needed.  The database should be implemented as a class that contains a dynamic array of flights (flight records being instances of another class). The database class should have at least the following functionality:

• A default constructor that creates a correctly initialized empty database.
• A destructor that cleans up all dynamic memory that was allocated by the database object.

The flight class should have at least the following functionality:

• An overloaded = operator to assign a flight object.
• An overloaded == operator to test if two flights have the same departure location, arrival location, and date of departure.
• a copy constructor

You will need to add additional operations to this class, of course, to implement the rest of the program.

Implementation Hints

As is usually the case, you will find it very helpful to do some designing before you start writing detailed code.  What is the high-level structure of the code?  What sort of data structure operations are needed to process the various commands?

A few specific suggestions and reminders:

• You need to pick some default initial capacity for the database class.  If you start with an artificially small size like 3 or 4, it will be easier to ensure that your tests exercise the code that dynamically expands the array. 
• Exploit the class that you design to hold the flight database.  Besides having one instance of this class to hold the complete database, you may find it very useful to create other instances to hold the partial lists accumulated by various reservation queries.

Testing

Think about interesting test cases for your program. A few suggestions (by no means a complete list!):

• Performing queries on an empty database.
• Reading empty files (with a single blank line).
• Reading files that change some or all existing records.
• Performing reservation queries which are empty.

Report

You know the drill by now: planning, implementation, testing, what you’ve learned.

Note: When describing the implementation, please don’t repeat stuff that is already documented in the code. Instead, describe what was problematic or interesting in your implementation, and how you handled these cases.

Sample Program

There is no sample program for this assignment.  In cases where the specification is not clear, you may need to make some reasonable assumptions.  Feel free to discuss issues about the specifications on the course newsgroup, in sections, with your colleagues, etc.

Electronic Submission

When you've finished your program, turn in the program code (.cpp and .h files only) using the turn-in form. Print out the receipt that appears, staple it and your written report together, and hand it in during quiz section.