CS 21: The Imperative Paradigm: Unix and C

Fall Semester 2004
Swarthmore College

Professor: Tia Newhall Section 1: TR 9:55-11:10, Sci. Center 240 Section 2: TR 2:40-3:55, Sci. Center 240 Email: Office: 249 Science Center Phone: 690-5637 Office hours: 2:30-3:30 W, 3:00-4:00 F, and by appointment

Contents

Course Description

This course introduces students to fundamental ideas in computer science using the C programming language and the Unix operating system environment. Class periods will consist of a combination of lectures and hands-on interaction at the computer. Topics to be covered include an overview of the Unix operating system, elementary Unix tools, modular software design, recursion and iteration, sorting and searching, abstract data types and their representations, lists, trees, informal analysis of algorithms, and a thorough introduction to C programming, including control structures, functions and procedural abstraction, libraries and modules, arrays, pointers, string manipulation, file processing, and records.

We will be paying particular attention to developing a good programming style. Your homework grade will be strongly influenced by the legibility of your code, so it is very important to develop a clear, logical, aesthetically pleasing programming style, making judicious use (but not overuse) of comments, whitespace, well-chosen variable names, and a consistent indentation style. There will be numerous programming assignments illustrating the concepts covered in class.

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How to Succeed in CS21

• Read the material before you come to class.
  Don't worry about total comprehension, but at least get a feel for what we will be covering that week. If you have some understanding of the material coming into class, it will be easier for you to ask questions during class, rather than later when help may not be available. Additionally, we often do lab exercises during class. This is an important part of the learning process, as these exercises give you immediate experience with the material we are covering. If you read the book before you come to class, you'll be able to complete these exercises more easily.
• Ask questions if you don't understand.
  This means both during class and while doing your homework. This class continually builds on previous material, so if you don't understand something one week, it will continue to be a problem the next week, and the week after that, and so on. If you need help, ask your classmates (make sure you have read the "Homework Scenarios" section below first), attend the clinics, come talk with me during my office hours, or email me your question.
• Start the homework assignments early.
  I realize this one is not always easy to do, but if you can get in the habit of doing this, you will be much better off. If you get stuck early (i.e., not two hours before it is due), there will be time to look for help. In addition, if you start early enough, you can take a break, go do something else, and come back later. I find I always have at least a few new ideas when I come back to a problem after a break. If you wait until the last minute, you can't do this.
• Practice, practice, practice.
  The only effective way to learn the material and pass the exams is to consistently do the homework. Finish all of the assigned programs (and do some extras, for fun!). Even if you don't get them done on time, they will still help you learn the material.
• Seek help early and often.
  Because course material builds on previous material, it is essential to your success in this class that you keep up with the course material. If you are having difficulty with a programming assignment, if you didn't follow something covered in lecture, if you feel you need some extra help understanding or practicing some of the course material, or if you just want to discuss something from a lecture, an assignment, or the text, please come to my office hours. Also, CS21 clinicians are available to help you with programming assignments during CS21 clinic hours each week.

Grading

Homework

Your homework assignments will be turned in electronically, using a special cs21handin program (to be explained in class). Late homework is not accepted. However, if you miss a deadline, you are strongly encouraged to complete the assignment anyway, since this really is the only effective way to learn the material.

Because many students feel they learn more through collaboration, you may work jointly with one other person on some designated assignments (although you may work alone if you wish). No more than two people should work together. If you work with someone else, you must submit a single, joint assignment with both names clearly indicated at the top of your program file(s). I will let you know which assignments you are allowed to collaborate on.

Homework assignments will be given a numerical grade according to the criteria shown below. Note that a program that works 100% correctly gets a 3. In order to get an 4, your program also needs to be clearly organized and well-documented (but this doesn't mean over-documented!). The numerical grades will be scaled in some way so that the difference between a 4 and a 3 is more like the difference between an A and a B grade.

4 correct, logically designed, well-documented, efficient
3 correct, but has stylistic problems
2 partially correct
1 does not compile or execute

If there are known problems with your code, you should describe these problems in a comment at the top of your program file.

About the CS Lab

We will distribute MicroProx tags to attach to your student ID sometime in the first or second week of classes. These will allow you entry to the CS Lab and entry into the Science Center after building hours. You should use the door between Martin and Cornell to get into the building after midnight.

Academic Integrity

The College's Judiciary Committee (CJC) handles plagiarism offenses. The penalties for plagiarism are quite severe: usually the first offense leads to failure in the course, but it may additionally result in suspension. The following constitutes plagiarism on CS programming assignments:

Under no circumstances may you hand in work done with (or by) someone else under your own name. Your code should never be shared with anyone; you may not examine or use code belonging to someone else, nor may you let anyone else look at or make a copy of your code. This includes sharing solutions after the due date of the assignment. Failure to abide by these rules constitutes academic dishonesty and will lead to a hearing of the College Judiciary Committee.

The exception is that you may use code that the instructors have distributed in class and code from the book (you should cite this code as coming from the instructor or from the book). Also, if you work with a partner, then you and your partner may share code for the particular assignment on which you work jointly (again, both your names must appear in the comment at the top of the file). Additionally, CS21 clinicians are allowed to help you with your code.

Discussing ideas and approaches to problems with others on a general level is fine (in fact, we encourage you to discuss general strategies with each other), but you should never read anyone else's code or let anyone else read your code. If you are in doubt about some help that you received, then credit the person(s) from whom you got help and discuss the situation with your instructor.

For some examples of what we consider "okay" and "not okay" collaboration, look at the scenarios below.

Homework Scenarios

• Late Thursday night, after working for a few hours on this week's CS21 homework, you realize you are stuck on one particular function. Instead of working more, and possibly not making any progress, you decide to get a good night's sleep and visit your instructor during office hours the next day.
• After working on a program for a few hours, you realize you are stuck with one particular concept. You look around the Sun Lab, find someone in the class, and ask them for help. After explaining what you are trying to do, your classmate points out a flaw in your idea, and gets you started in a new direction. After successfully completing the program, you add a comment at the top of the code stating who you received help from.
• You had trouble with the last homework assignment, so you ask someone in class if they would like to work as a team on this week's assignment. You get together well before the assignment is due, and discuss the first program. After figuring out a reasonable algorithm, you work together to type in the program and debug it. When you are finished with the program, you put both of your names in the comments at the top, and turn it in as a team.

• No matter what you do, you can't seem to get your program to work and are getting very frustrated. A friend of yours comes into the Sun Lab who you know has already finished this week's homework. You ask her for help, but since she is busy working on an assignment in another class, she offers to print out a copy of her code for you to look at.
• After working on a program for a few hours, you realize you are not making any progress with one particular function. As no one is around to ask for help, you take a look at your friend's program in his home directory, to see how he wrote the function.
• Late Sunday night, after just starting this week's CS21 homework a few hours ago, you realize you will never finish before the deadline. After searching through many directories, you finally locate another student's homework and copy it to your home directory. After modifying a few comments, you turn in the copied program as your own.

Clinics

• Saturdays 2pm-5pm: Ken Long
• Sundays 4:30-7:30pm: Dimitar Enchev

  

During clinic hours there will be a clinician (a student who has previously taken this course) available to help with your weekly programming assignments.

Schedule

WEEK	DATES	TOPIC	READING	ANNOUNCEMENTS	IN-CLASS	HOMEWORK
1	8/31, 9/2	Introduction to C Programming	1, 2	Using Unix I: Tues. 4-5pm or Wed. 8-9pm (in CS lab)	Tues Thurs	hw1 hw2
2	9/7, 9/9	Problem Solving	3, 4	Add/Drop ends 9/10 Using UnixII Tues. 4-5pm or Wed. 8-9pm C Code Style Guide (look at "Line Length" for tips on how to not wrap lines)	Tues Thurs	hw3
3	9/14, 9/16	Functions and Debugging	5, 6	-	Tues	hw4
4	9/21, 9/23	Libraries and Graphics Libraries and Random Numbers	7, 8	-	Tues	hw5
5	9/28, 9/30	More Random Numbers	8	Exam 1 Thurs. 9/30 Exam 1 Topics Tips for taking Exams	Tues	hw6
6	10/5, 10/7	Arrays	11	-	Tues Thurs	hw7 Read C Style Guide about commenting functions: C Style Guide
-	-	Fall Break	-	Fall Break	-	-
7	10/19, 10/21	Searching, Sorting, and Analysis of Algorithms	12, 17.3	Clinic Tues. 6:30-9:30 no Thursday clinic this week	Tues Thurs	hw8
8	10/26, 10/28	Pointers	13	-	Tues Thurs	-
9	11/2, 11/4	Pointers cont. Characters and Strings	9.2, 14 Pointers	-	T&TH	hw9
10	11/9, 11/11	Characters and Strings	9.2, 14 chars strings	Exam 2 Thurs. 11/11 Exam 2 topics Office Hours: Tues: 4-5, Fri: 3-4	-	-
11	11/16, 11/18	Reading and writing files, using make files	15	-	chars strings Tues file I/O Thurs	hw10 Part 2 due Wed. Dec. 1
12	11/23	Records	16	Thanksgiving vacation 11/25	Tues	-
13	11/30, 12/2	Linked Lists	17.2, handouts Linked Lists	-	Tues Thurs	hw11 extra clinic hours: Mon Dec. 6 7:30-10:30pm Tues. Dec. 7, 7-9pm
14	12/7	Binary Trees	-	Final Exam: Dec. 10th, 7-10pm, room 101 Sci. Center Exam 3 Topics	-	-

• cs21handin: how to use the cs21handin program to turn in assignments.
• useful Unix commands: handout from the first day of class.
• C Code Style Guide Read this early and often.
• Safe File Sharing for Group Projects

• CS Deptpartment's Unix Help Pages
• My Unix Documentation make, tar, cvs, rcs, debugging tools, editors, email, protecting and sharing files, C style guide, ...
• Compiling, Linking and Debugging Tips for C
• Recovering Lost Files What to do if you accidentally delete a file