Checklist: Conditionals and Loops

Frequently Asked Questions

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

What preparation do I need before beginning this assignment? Read Sections 1.2 and 1.3 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.

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

Submission

Submission. Don't forget to submit all files, including the completed readme_loops.txt file. Include your name, PennKey, and Section in the file header at the top of each file. You may resubmit as many times as you like, but the time at which you submit your last file will count as your submission time. If you resubmit, you only need to upload the files that have changed; you may leave the other upload fields blank.

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.

A drunkard's walk. This is similar in many ways to the gambler's ruin example from lecture and the textbook. The key to building a larger program is developing it incrementally.

• Random walker. First, think about what variables you need to maintain. You certainly need to read in and store the command-line argument N. You also need to store the current location (x, y) of the random walker. What should be the type of the variables x and y? What should be their initial values? To choose a random direction, consider using the idiom from Section 1.2 to generate a random integer in a given range.

• Random walkers. To get started, copy RandomWalker.java to a file RandomWalkers.java. Now, think about what additional variables you need to maintain. You certainly need to read in and store the command-line arguments N and T. In addition to the current location (x, y) of the random walker, you need an accumulator variable, say totalSquaredDist, that stores the total sum of squared distances so far. Nest the loop inside an outer loop that repeats T times and add code to update totalSquaredDist after each time through the outer loop.

Enrichment

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