Software Hygiene for Introductory Computer Science

June 19th, 1998, minor changes 1/2/00

Introduction

Because electronic information can be moved around and replicated so easily, there is always the danger that someone may get hold of your homework solution and use it to cheat. Software Hygiene is a set of rules and procedures you can follow that will minimize the risk that you get implicated in a case of cheating. This document will hopefully eliminate most of the ambiguity about what constitutes cheating in this course.

Even if you know with all your heart that you would never deliberately cheat, it is still possible for someone to get hold of your source code if you're not careful. You are responsible for the security of your own documents. What this means is that if your submission is found to correlate too strongly with some other submission, YOU BOTH MAY BE CONSIDERED RESPONSIBLE, even if the other party copied off of you. So be careful, and follow the rules outlined here. They should ensure that you avoid these sorts of entanglements.

1. Use of Lab Facilities

The lab is a potentially unhygenic place to work. You are sharing a resource (the computer and network) with many other students, some of whom may attempt to take advantage of you. Here are some tips to follow:

Do not leave your terminal unattended! An unattended terminal is an invitation to raid your data. If you need to be away from the computer, lock the screen. This prevents others from accessing the machine while you're away, but doesn't log you out.
Do not leave your printouts unattended. If you send your work to the printer, make sure you pick it up immediately. It's very easy for someone to simply take your printout and copy your program.
Do not leave your belongings unattended. If you're carrying other printouts, rough work, floppy disks, or anything else that may contain your private work, make sure you don't let others get to it.
USE "CLEANUP AND RESTART" INSTEAD OF LOGGING OUT! This one is extremely important. Simply logging out may leave all kinds of temporary files on the local hard drive, which the next user could grab. The "restart the computer" (the little lightning bolt icon in the start menu) makes sure that you don't leave any files behind when you leave the IPL. Don't ever, ever just log out.
Use "cleanup and restart" when you log in. This one is less crucial, but still a very good idea. When you get a machine in the IPL, log in and use "cleanup and restart". When the machine restarts, log in again. The extra use of "cleanup and restart" prevents anybody from leaving hidden programs on the machine that can be used to examine your files.

2. Use of Mailing Lists and Newsgroups

The course mailing lists and newsgroups are an excellent way for you to help each other out. You are encouraged to share ideas and tips with each other, and discuss (in general terms) possible solutions to the homework problems. Here's what to remember when using the mailing lists:

DO NOT POST YOUR PROGRAM! This is the first and most important rule pertaining to the mailing lists. Do not make any portion of your program code available on a mailing list. You will be severely reprimanded if you do so.

Of course, there will be times when you have some sort of C++ question and you would like to put source code in a message. Instead of cutting and pasting directly from your homework, consider one of the following:

Create a fresh example that isolates the problem. If the bug is in some function, throw out everything in the function that works until all you're left with is the code that causes the bug. Rename the variables to a,b,c, etc. (variable names can give away a lot about a function). One advantage of doing this is that often, in the process of whittling down a function to isolate the error, you discover what the error was!
Post pseudocode instead of C++ code. Pseudocode is typically higher-level than C++ and doesn't contain enough information to easily reconstruct the original code. It's just an outline of what a function does. If you problem is in the conceptual structure of an algorithm, consider using this approach.

3. Working With Others

Despite all this paranoia, you are still encouraged to work together on the assignments to a limited extent. You just have to be careful about what "working together" means.

DO NOT SHARE YOUR PROGRAM WITH OTHERS! The easiest way to avoid duplication is to never look at anyone else's code. So don't work together in front of a computer. If you want to think about the homework in a group, go somewhere where there aren't any computers. A whiteboard is always a good thing to have handy...
When you're working in a group, don't write code together. Think about the problem abstractly. Use diagrams, pictures, text, and even pseudocode, but don't generate C++ code as a group.
Ideally, when you work with others, don't take written notes to refer to later. If you can walk away from the meeting and understand how to proceed on the homework without any sort of written record, then chances are you understand the material.
From time to time, someone may ask you to look at their code in the lab, for instance if they have a bug they can't find. THIS IS OKAY. You can help other people fix problems in their code, as long as they've already written it (an unwritten function is not a bug you can help someone with). But don't send or receive code via email, even for the purposes of debugging. Keep your code to yourself.

Occasionally, assignments will allow small groups (2 or 3) of students to work together. In these cases, the rules presented above simply expand to encompass the group. IF the assignment calls for group submission, you may collaborate on all aspects of the design and implementation of the homework, but you may NOT share your work with other groups.