ITEC 380 2016fall ibarland

home—lectures—recipe—exams—hws—D2L—breeze (snow day; distance)

hw04
structs
donkey kong structs

Due:
Sep.28 (Wed) 15:00, D2L and hardcopy.
Your submitted file should be named “hw04.rkt”, plus any .java files..

Standard instructions for all homeworks:

• Your name, the assignment-number, and the URL of this assignment must be in a comment at the start of the file.
• Any code which results in syntax errors will generally not earn more than 50% of the points-possible. For grading, I will ignore any commented-out code (unless the problem is explicitly asking for commented-out code, ’course).
• If your hardcopy is more than 1page, it must be stapled.
• Format well (in particular, each open-paren should be preceded by a space or start-of-line, for now).

1. (This is the completion of qz02, from D2L.) Consider the following information, which might be part of a sports-simulation:

   A team is:

   • a name (non-empty string), AND
   • an offense rating (real number), AND
   • a defense rating (real number).

   (5pts) Give a data definition (including examples of the data, and the template for any function which processes a team), as per steps 1-3 of the design recipe. Give at least three examples of a team.

   (10pts) We'll say one team is “greater” than another if its offense is higher than the other's defense, and its defense is higher than the other's offense. Write the function team>? to implement this. Follow all the steps of the design recipe. As always, be sure to think about enough test-cases to cover the interesting situations (5 of the pts). (In this case, six or seven should suffice, if they each cover a different situation.)

2. Familiarize yourself with the Donkey Kong arcade game. We will write a simplified version which does not need to deal with: score, sound, multiple levels, angled platforms (though that's possible as a challenge) any sort of deranged ape who throws barrels (new barrels will just appear), broken ladders, evil barrels that fall down stairs or through floors, or number-of-lives. You will need to deal with barrels that roll, jumping, and platforms.
   1. (5pts) What are three different types of things (objects) in the game, that our program will need to model?
   2. (5pts) For one of the types in (a) above give a Java class definition for it (fields and the “natural” constructor only). Create two or three instances of the class (presumably in a test method that does nothing else). You'll submit a .java file along with a .rkt file.
   3. (5pts) Repeat the previous step (b), but in racket. (That is, give a struct-definition w/ a comment indicating the field-types, and create at same two examples.) All field-names should correspond directly — e.g. if a Java field was named “numPages”, then the racket name would be “num-pages”.
   Note that we are not writing any functions, so we don't have any check-expects. We are just doing steps 1 and 2 (only) of the design recipe (in both Java and in racket), for only one of the types.

Hints:

• Imagine a friend has two different snap-shots of the game; what is the minimal information that your friend needs to tell you so that you can always properly draw/construct an image of that object on the screen.

• Do NOT include information which never changes (is “invariant”) for a class. For example, if all instances of an object are always the same color, you wouldn't have a field for the color.

home—lectures—recipe—exams—hws—D2L—breeze (snow day; distance)

©2016, Ian Barland, Radford University Last modified 2016.Oct.31 (Mon)

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