COMP 105 Introduction to Computer Science

Kalamazoo College Computer Science Program Fall 2008

Mini-Lab 7: Arrays*

Introduction

The purpose of this mini-lab is to practice working with arrays (Chapter 10) and random access.

Exercises

• Knock-knock *

  In this exercise we will create a scene in which one character tells another character a random knock-knock joke.

  Start out by adding two characters to a scene. Decide on what jokes you want to use. You should have at least four of them.

  Create a tellRandomJoke method. (Should this be a world-level method or a class-level method? Think about what its purpose is.) Inside this method, create two array variables, one to hold the names of who's there in the knock-knock jokes, and the other to hold the punchlines. You will need to add the name and punchline items to the appropriate arrays when the array variables are created. (Why?)

  The first two lines in the method should alternate characters saying the first two lines of the joke. (Character 1: "Knock-knock". Character 2: "Who's there?") You may want to change the font, and/or set the duration of the sayings to make them visible longer.

  Now we want to use a random number, call it i, to get which joke we want to say. Create a new class-level variable to hold an integer. (The initial value does not matter.) In the program, set the value of i to a placeholder value (i.e., just some value, like 0 or 1), by dragging the variable into the code and choosing to set value. Next, look at the world-level functions. Under the random functions, choose the random number function, and drag it onto the value for i. Then click on the "more" option to set its minimum, maximum, and integerOnly attributes to appropriate values. This value represents an index in the array, so its minimum should be 0, and its maximum should be the number of jokes you have. Set the integerOnly attribute to be true, otherwise the function may produce values with decimal places, like 1.25, 0.05, 3.647, etc..

  Now we can use this value of i to select the appropriate array values from the array of names and the array of punchlines to finish the joke. Your characters should continue to alternate lines of the joke using this information.

  To test that your joke-telling scenario is working correctly, put an infinite loop in the world.my first method that calls the tellRandomJoke method.

  Modify the tellRandomJoke method to take the characters as parameters. You will need two parameters, and will need to modify the joke-telling sequence to use the parameters as the characters, instead of the actual characters. Update the call to tellRandomJoke in the world.my first method to include your characters as the parameters.

• Extras **

  • Make the joke-receiver do some sort of action to indicate the "lameness" of the joke.
  • Create events so that when a character is clicked on, that character becomes the joke-teller.