Programming Assignment Checklist: Loops and Arrays

Frequently Asked Questions

What are the goals of this assignment? To write several small Java programs so that you get accustomed to: using conditionals, loops and arrays and to debugging your code.

What preparation do I need before beginning this assignment? Read Sections 1.3 and 1.4 of the textbook. You may also find it instructive to work through some of the other exercises and look at the solutions on the booksite afterwards.

How should I format my Java code? How much do I need to comment my code? Follow the style guidelines. Also, don't forget to put your name, precept, and login in the header of every file.

I have the constants 6, 10, 51, 60, and 61 sprinkled through my TenDice program. Is there a better way? Yes, give your constants meaningful symbolic names, such as SIDES or NUMBER_OF_DICE. This will make your code easier to read, maintain, and debug. Beginning on this assignment, you will lose points for not doing so.

Do I have to use command-line arguments to read the inputs? Yes, or you will lose a substantial number of points.

Submission

Submission. When you submit, be sure to click the Check All Submitted Files button. Make sure that you submitted the right files and that they compile cleanly. You may resubmit a file after making corrections. The dropbox system will always ask you to confirm that you want to overwrite the previously submitted file.

Possible Progress Steps

These are purely suggestions for how you might make progress. You do not have to follow these steps. The key to writing correct programs is to develop them incrementally, testing after each step.

BoyAndGirl.

• First, think about what variables you need to maintain. You certainly need a counter for the number of children.

• How will you tell when there is at least one of each gender? (That will be the condition of your while loop.)

BoysAndGirls.

• To get started, copy BoyAndGirl.java to a file BoysAndGirls.java.

• Now, think about what additional variables you need to maintain. You certainly need to read in and store the command-line argument T.

• You will also need to count up ALL the children in order to compute the average number of children needed to achieve the goal of both genders.

• You will also need to keep a frequency counter for each of the four possible categories (2, 3, 4, 5 and more).

• Nest the while loop inside an outer loop that repeats T times and add code to update child count and frequency counts after each trial.

Dice and the Gaussian distribution.

• Write a program that prints the result of rolling one fair die. To generate a random die roll, use the idiom from Section 1.2 to generate a random integer between 0 and N-1, and modify it slightly to get one in the desired range.

• Add a loop to print the sum of rolling 10 fair dice.

• Add a second loop to repeat this N times, printing out the sum after each trial. (This printing of the sum is for testing purposes only. Remember to remove it from your final version.)

• Maintain an array a[] so that a[k] stores the number of times the sum is exactly k.

Enrichment

Here are some famous and not-so-famous quotations about learning to program.