CSc265 -- Exercise 3
DUE: midnight, Tuesday 5 November 1996
Overview
The purpose of this exercise is to provide experience with using dbx.
You are provided with the source code of the compress and
uncompress programs.
(These are the same compress and uncompress programs that
are commonly used in Unix and other systems to reduce file sizes --
typically by 50% to 60% depending on the nature of the file.)
You must compile the program following the instructions below.
Then you must use dbx to run the program and answer some questions
about the program's operation.
Preparing for the Assignment
The directory /home/csc265/Exercises/Ex3 contains three files,
named README, testdata and compress.c.
You should copy all three files into your own directory.
You should execute the two commands below:
% cc -g -o compress compress.c
% ln compress uncompress
There will be a couple of warning messages produced by the compiler;
you can safely ignore these messages.
The commands create two additional entries in your directory named
compress and uncompress.
These two entries both refer to the same executable file.
(One of the first actions of the program is to test what command name
was used to invoke it and that selects between the compression and
decompression functions.)
Notes:
- Documentation for the compress/uncompress
program is available on most Unix systems. You can execute
% man compress
to read about the various command-line options.
- The testdata file is actually a copy of the
man compress output.
- If you want to learn about how the compression works, the book
Text Compression by T. C. Bell, I. H. Witten and J. G. Cleary
is highly recommended.
Submitting Your Solutions
The README file is in the form of a questionnaire.
Use vi or your favourite text editor to add your answers to that file.
Then e-mail the updated README file to the csc265 account.
The following command will perform that task:
% mail -s 'Exercise 3 submission' csc265@gulf < README
Grading Criteria
You will receive ten points for each question answered correctly.
Submit the assignment only once.
Only the first submission will be graded.