A9-Getting Classy

Table of Contents


Objectives

  • Develop classes and construct objects.
  • Hide data using the keyword private.
  • Write member functions that access private data.
  • Code multiple constructors to initialize private data.
  • Call member functions of objects.

Academic Honesty

Read the Scholastic Honesty Policy and Assignment Integrity policies of the syllabus. Here are some clarifications for this particular assignment:

  • You are encouraged to work with one other student of this class following the rules of Pair Programming for Homework Assignments. If you choose to pair program, there is a bonus applied.
  • You may not give a copy of your code to your designated pair-programming partner if you did not develop the code together.
  • You may not look at another student's code until you complete and submit this assignment, except for code you develop code together with your pair-programming partner.
  • You may get help from people other than your pair-programming partner if you get stuck, but only if they do not show or tell you the code to type.

Preparation

  1. Make sure you have completed the exercises from lesson 9.
  2. Complete the Review Exercises in CodeLab 9. These exercises will help prepare you for the problem-solving programs and should be completed first.

Project Specifications

Your solutions to these projects must use only techniques we have covered so far.

Programming Style

For all programs, remember to follow all the style rules we have covered, as well as the new rules, including:

  1. Class naming conventions (See: Class Names) new!
  2. Indentation in classes and placement of curly braces new!
  3. Every function declaration (prototype) in the class, including constructor functions, have a function comment block new!
  4. Every file has a file comment block
  5. No magic numbers (See: No Magic Numbers)

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Project 1: A Class Wombat

Wombats are furry and short-legged marsupials native to Australia. They eat plant matter and are adapted for gnawing tough vegetation. Wombats have strong legs and powerful claws, digging extensive burrow systems like gophers. However, growing to about 40 inches in length and weighing about 60 pounds, wombats are much larger and stronger than gophers.

Being marsupials, mother wombats have a pouch to carry their young joey's. Interestingly, a wombats pouch is backwards facing so when it digs it does not spread dirt over its young [1]. Newborn wombat's stay in their mother's pouch for about a year. Thus a Wombat starts it's life apart from its mother when it is about one year old.

Project Specifications
  1. Write a declaration and a definition for a class named Wombat along with a short main() function to test the class code. See lesson 9.2.2 to get started.
  2. Name the source code file wombat.cpp and include all your code in this single file.

    Be careful of the spelling, including capitalization, as you will lose points for a misspelled name. Naming is important in programming.

  3. Have no user input for this project. Testing code for the program is hard-coded in main().

    Do NOT use any keyboard input streams, like cin, in this project. If you have a cin statement in your code, you will get a low score.

  4. The Wombat class must contain exactly (no more and no less than) two member variables declared private:
    1. string name
    2. int age
    See lesson 9.2.3 for an example.
  5. Write function declarations (prototypes) inside the class and separately define (implement) all the member functions outside the class declaration (curly braces of the class), including constructor functions.
  6. Write a default constructor that sets the name to "Hairy" and the age to 1. See lesson 9.2.5 for an example.
  7. Write a two-parameter constructor that sets the name and age member variables to the parameter values. The parameters must be coded in the order of name followed by age. See lesson 9.3.2 for examples.
  8. Write one "get" function for each of the member variables that returns the variable's current value. The name of the function must follow the naming standards for "get" functions, which is the name of the variable with the prefix word "get". See lesson 9.3.4 for examples.
  9. All non-mutator functions must include the keyword const as discussed in lesson 9.3.4 under Accessor Functions and in the textbook on pages 402-403 under the section on, "const Correctness".
  10. Write a member function for the Wombat class named say() with the following signature: (2 points)
    /**
        Randomly selects a single sound from the sounds array.
    
        @param sounds An array of sounds to choose from.
        @param size The number of elements in the array.
        @return A randomly selected sound from the list of sounds.
    */
    string say(string sounds[], int size) const;
    

    Call the function at least once in your story. When called, the function selects one of the sounds from the array parameter at random and returns one of the sounds made by a Wombat. The six sounds made by a Wombat are: "squeal", "hiss", "grunt", "growl", "cough", and "click". All are printed without the double quotes.

  11. Example Run: In your main() function, construct two or more Wombat objects, using both the default constructor and the overloaded constructor. Then write a story that calls all the member functions of the class at least one time. For example:
    During a trip to the zoo, I saw a Wombat named Hairy, who was 1 year old
    and stationed near the dingo cage. I do not think Hairy liked the dingoes
    because he would growl and squeal when any dingo was nearby. Another Wombat,
    named Wendy, seemed indifferent.
    They being a native of Australia, I gave 'em a cheery "G' day Mate!".
    Upon hearing my voice Wendy seemed to want my popcorn. Hairy just turned
    his back, made a grunt, and burrowed into the ground.
    

    In the above example story, the text in aqua italics shows the output of member functions calls. Your program does NOT print the characters using colors or italics. Have fun and make up your own wombat story. See lessons 9.2.3 and 9.3.3 for how to construct objects from classes. See lesson 9.3.4 on how to access member variables.

  12. After displaying the story, exit the program.
  13. Submit this project with the rest of the assignment as described in Deliverables.
Hints:
  • We only need the functions listed in the specifications above, though there is no penalty for adding more functions in this project. However, consider if another function is actually needed before adding one. Best practice is to minimize the functions provided.
References and More Information
  1. Wombat: Wikipedia article.
  2. The 25 Most Important Wombats Of All Time: BuzzFeed

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Project 2: Movie Money

Movies generate income from several sources including movie theater receipts, home video, television and merchandising. However, movie theaters are the main way the success of a film is measured. [1]

Inflation has taken away from the monetary success ratings of films in the 60s and 70s. Ticket prices in the 60s and 70s were $1 to $2 but now average over $9 [2]. However, some of these franchises from that period are still active such as Star Wars, Superman, James Bond and Star Trek. When adjusted for inflation, some older films still have respectable gross receipts by today's standards [1, 3].

Project Specifications
  1. Write a declaration and a definition for a class named Movie along with a short main() function to test the class code.
  2. Name the source code file movie.cpp and include all your code in this single file.

    Be careful of the spelling, including capitalization, as you will lose points for a misspelled name. Naming is important in programming.

  3. Have no user input for this project. Testing code for the program is hard-coded in main().

    Do NOT use any keyboard input streams, like cin, in this project. If you have a cin statement in your code, you will get a low score.

  4. The Movie class must contain exactly (no more and no less than) three member variables declared private:
    1. string title
    2. int year
    3. double revenue (in millions adjusted for inflation)
  5. Declare only the following functions (prototypes) inside the class braces and separately define (implement) the functions outside the class declaration (curly braces of the class):
    1. A default constructor that sets the numerical types to zero (0).
    2. A three-parameter constructor that sets the title, year, and revenue member variables to the parameter values. The parameters must be coded in the order of title, year, and revenue.
    3. One "get" function for each of the member variables that returns the variable's current value. The name of the function must follow the naming standards for "get" functions, which is the name of the variable with the prefix word "get".
    4. One "set" function for each member variable with a single parameter that sets a value for a member variable. The name of the function must follow the naming standards for "set" functions, which is the name of the variable with the prefix "set".
    5. Accessor function print() that has no parameters and returns no values, but displays the data of the object all on one line like this:
      Star Wars, Episode IV: A New Hope    1977   3041.3
      Text must be left justified and numbers right justified with the correct number of decimal places. The data displayed in order are:
      1. title
      2. year
      3. revenue
    6. Do not add any extra member functions than the above.

    Note: even though you must write the get functions, you may not need to actually call them for this assignment. We will be using the get functions in future assignments.

  6. All non-mutator functions must include the keyword const as discussed in lesson 9.2.4 under Accessor Functions and in the textbook on pages 402-403 under the section on "const Correctness".
  7. In the movie.cpp file, write a main() function to do the following:
    1. Construct at least the three Movie objects.
    2. Set values (title, year, and revenue) for two objects using the three-parameter constructor and for one object using the default constructor with "set" functions.
    3. Display output for all 3 objects as shown in the Example Output specification.

    Have no user input for this project. Instead write code to do the above in main() for testing. Do NOT use any keyboard input streams, like cin, in this project. If you have a cin statement in your code, you will get a low score.

  8. Example Run: When you run the program you must see the following output without any user input.
    Famous Movie List:
    Title                                Year  Revenue (m$)*
    Avatar                               2009   3251.0
    Star Wars, Episode IV: A New Hope    1977   3041.3
    Black Panther                        2018   1346.9
    *m$: millions of dollars
    

    You may change the spacing between columns but columns must line up as shown, with names left justified and numbers right justified with one decimal point for revenue. See the references below and feel free to come up with your own movie names and data.

  9. Create the correct spacing for the output using the setw() formatting manipulator described on pages 49-51 (1/e: 53-55) of the textbook. In addition, you will need to use the left and right formatting manipulators. To use these manipulators, include the iomanip library. Align text or numbers in a setw() field using left or right to align the data. For example:
    cout << setw(35) << left << title; // aligns data left in 35 character field
    
  10. After displaying the output, exit the program.
  11. Submit the source code file movie.cpp with the rest of the assignment as described in Deliverables.
Hints:
  • The width constants in the example run are
    const int TITLE_WIDTH = 35;
    const int YEAR_WIDTH = 6;
    const int REVENUE_WIDTH = 9;
    
  • Do NOT put const variables inside the class. See spec 4 above.
References and More Information
  1. List of highest-grossing films: Wikipedia
  2. Adjusting for Ticket Price Inflation: Box Office Mojo
  3. Domestic Grosses: Adjusted for Ticket Price Inflation: Box Office Mojo
  4. All Time Worldwide Box Office: The Numbers
  5. All Time Box Office: Box Office Mojo

Extra Credit

The following are worth extra credit points if the main program works well:

  1. Complete the assignment using pair programming. (2 points)
  2. Add a function named toString() to class Movie that has no parameters and returns a string containing all the data about the movie. Call the function one time to show that it works. (2 points)

    The function does NOT print any values and must NOT use cout. Instead, the function must return a string with one line of text like that shown below.

    Star Wars, Episode IV: A New Hope    1977   3041.3
    

    Once returned, print the string within main() using code like:

    cout << starWars.toString() << endl;
    

    Note that this extra credit will require you to convert numbers to strings. Research stringstream for the conversion and provide an attribution for the source of your stringstream information, either a URL or book and page number. No attribution means no credit.

Make certain that your README.txt file describes any extra credit attempted.

Tutorial Lab

In preparation for next weeks lessons, complete the following:

  1. Read the assigned reading in the textbook
  2. Complete the Tutorial Exercises in CodeLab 9 before the specified due date.

    Refer to the assigned reading for the next lesson to help you understand the problems. Also, you can use the online lecture notes for more information as the notes become available. You can look at solutions if you miss your first few attempts and are stuck by clicking the "Solution" tab.

Grading Criteria

The instructor will evaluate your assignment using the following criteria. Thus you should check your assignment against these criteria to maximize your score.

Each criteria represents a specific achievement of your assignment and has a scoring guide. The scoring guide explains the possible scores you can receive. Some scoring guides have a list of indicators. These indicators are a sign of meeting, or a symptom of not meeting, the specific criterion. Note that a single indicator may not always be reliable or appropriate in a given context. However, as a group, they show the condition of meeting the criterion.

For information on grading policies, including interpretation of scores, see the syllabus.

Lesson Exercises

  • 2: All lesson exercises attempted and turned in
  • 1: Some lesson exercises completed and turned in
  • 0: No lesson exercises completed or turned in

Class Functionality (x2)

  • 7: Demonstrates mastery of the assignment.
    • Applies concepts from the lessons appropriately
    • Meets all specifications with particularly elegant solutions
    • Runs to completion with no abnormal error conditions
    • Generates correctly formatted output
  • 6: Has all the functionality expected of the assignment with mostly correct formatting.
    • Demonstrates many techniques from the lesson
    • Attempts to meet all specifications
    • Generates correctly formatted output given correct input
    • May have one minor formatting error
  • 5: Has most of the functionality and format expected of the assignment
    • Demonstrates many techniques from the lesson
    • Attempts to meet all specifications
    • Implementation seems more complicated than necessary.
    • May have one or more formatting errors in output
    • May have one minor functional error
  • 4: Has most of the functionality expected of the assignment
    • Demonstrates some techniques from the lesson
    • Attempts to meet all but one of the specifications
    • Implementation seems excessively complicated.
    • May have many formatting errors in output
    • May have 2-3 minor functional errors
  • 3: Has some of the functionality expected of the assignment
    • Attempts to meet at least 1/2 of the specifications
    • Demonstrates many techniques from the lessons
    • Implementation seems excessively complicated.
    • May have more than 3 minor functional errors
    • Source code compiles with no errors or warnings
  • 2: Serious functional problems but shows significant effort and understanding
    • Attempts to meet less than 1/2 of the of the specifications
    • Has a major error or many minor errors
    • Implementation seems very convoluted
    • Demonstrates few techniques from the lessons
    • Source code compiles but may have multiple warnings
  • 1: Serious functional problems but shows some effort and understanding.
    • Does not compile but shows an attempt to meet most specifications
    • Implementation seems somewhat complete but has errors
    • Demonstrates some techniques from the lessons
  • 0: Minimal to no work apparent or made in an incorrect way.
    • Not turned in
    • Does not compile with little work apparent
    • Attempts to meet less than 1/2 of the of the specifications
    • Uses techniques not covered in the course so far

Program Style

  • 4: Code is well-documented including:
  • 3: Code has a minor documentation error.
  • 2: Code has some documentation errors or a missing file.
  • 1: Code has many documentation errors or a missing file and some errors.
  • 0: No apparent attempt to follow documentation standards or write documentation comments

CodeLab and Other Tutorial Exercises

Number completed correctly / number exercises * 8 and rounded up to the nearest integer.

README.txt File

  • 2: README.txt file submitted following the instructions
  • 1: README.txt file submitted but some information was missing
  • 0: No README.txt file submitted

Total possible: 30, plus extra credit

Deliverables

Submit your assignment to Canvas, in the assignment folder A9-Getting Classy, following the instructions for submitting homework. Include the following items for grading:

  1. README.txt file
  2. All the exercise files from Lesson 9
  3. wombat.cpp
  4. movie.cpp

Your assignment must work as submitted, so submit all the files needed to complete your assignment. Remember to test and double check your files before submitting them. If you make a mistake, you can resubmit up to the deadline. If you resubmit, you must include all your assignment files in the last submission as Canvas hides prior submissions.

Last Updated: November 04 2018 @15:08:37