Assignment 1 C strings

COMP 206– Assignment 1

Objectives:
Gain our first hands-on experience with coding software system specifications in C. Specific focus on
working with C strings, reading text files and structured output to standard output.
Instructions:
Write the two C programs specified in the following questions. Test them very carefully and pay careful
attention to detail, as marking will ensure that you program meets the specifications very precisely. Every
program you submit must compile with "gcc program_name" on mimi.cs.mcgill.ca without errors or
warnings. When run with the examples shown here, as well as additional correct inputs, the corresponding
correct output must be generated. If run with incorrect inputs, the program must never crash (segfault,
bus error, etc),but rather print informative errors and exit cleanly.
Automated Testing:
The eval.py script contained in the assignment folder can be used to ensure your program works well with
our automated grading. It will compile run several of the basic tests and report the results. To run it, place
your C files in a folder, and run "$ python <folder_name". You will see a fairly long report generated.
When everything works, you should see the string "Your program's output is the same as expected output:
True" for both questions. This is similar to the process we'll use for real grading, but that will include a
wider range of test cases, so do run your program directly yourself and ensure it always works!
Handing In:
Upon completion, create an archive file with both your C programs using the command:
$ tar –czf A1_submission.tar.gz q1_julia_explorer.c q2_calendar.c
Submit the resulting archive on My Courses.
Due Date:
1. For full marks: Friday Feb 9th
2. Final deadline (with 10% penalty): Tuesday Feb 13th
Question #1 – Explore the Julia Sets (40 marks)
A Julia Set is a construction from complex math that can be used to generate a wide range of fractal
patterns, with the chaotic property: very small changes in the initial conditions lead to dramatic changes
in the generated shape. A standard Linux tool, gnuplot, is capable of plotting a Julia Set from a simple text
script and we have provided you with the basis of this script as the attached file "shape_template.txt".
You will create a C program to automate the process of inserting the initial conditions, two floating point
numbers, into the correct place in the script, a simple token replacement. In case you try this on your own
computer, the command "sudo apt-get install gnuplot-x11" is likely to be helpful.
Write a program q1_julia_explorer.c that allows the user to produce Julia Set plots interactively:
1. Accept exactly three command-line arguments <file_path <a <b:
a. <file_path: A path to the provided "shape_template.txt" gnuplot script
i. Identify a correct shape_template.txt file as one your program can open for
reading, and which contains two "tags": #A# and #B#. For any incorrect file,
output "Error: bad file" and return with code –1.
b. <a: A floating point value a (which has meaning in the construction of the Juliaset)
c. <b: A floating point value b (which has meaning in the construction of the Juliaset)
d. For any problem with the a or b arguments, output "Error: bad float arg" and return –1
2. Produce a modified gnuplot script on standard out, where the modifications are exactly:
a. The #A# tag text is replaced with a, printed with 6 decimals (use %.6f)
b. The #B# tag text is replaced with b, printed with 6 decimals (use %.6f)
c. Note that the provided shape_template.txt is only an example. Your code should
definitely handle the tags in this file, but hardcode as little about it as possible, such that
any other file with the same tags can also be used for testing.
Examples test runs: 
Question #2 – Formatting the year (60 marks)
Write a C program named q2_calendar.c that prints one year’s full calendar to standard output.
1. Accept exactly 2 command-line arguments that control the calendar details:
a. Maximum number of characters DAYSIZE to print for the day-of-week labels, which
must be 2 or greater
b. The day-of-week that starts the year FIRSTDAY as an integer from 1 to 7 (1 is Sunday in
English)
2. Your output must precisely follow the format specification given by the following examples, so
you should make sure you can replicate them precisely. Note that the examples were cut off at
April only because we ran out of space on the page. The output must continue until Dec 30th
.
The full text specification of this format is on the next page.
Detailed calendar specification:
1. Accept exactly 2 command-line arguments:
a. Maximum number of characters DAYSIZE to print for the day-of-week labels, which
must be 2 or greater
b. The day-of-week that starts the year FIRSTDAY as an integer from 1 to 7 (1 is Sunday in
English)
2. Your output must precisely follow this specification (and shown in the examples below) for
printing a year's calendar.
a. Every row must begin and end with the one pipe symbol "|"
b. Each row contains (DAYSIZE+3) x 7 + 1 visible symbols, and a newline
c. Each month is composed of:
i. A full-wdith separator line of dashes "-"
ii. A line composed of the month’s full name, centered using spaces, with one less
space before than after if needed
iii. A separator line
d. A line with 7 columns of day labels, with pipes "|" in between. Each day label contains:
i. A single space
ii. The day-of-week name cut down to DAYSIZE characters if needed
iii. Additional spaces to pad up to DAYSIZE if needed
iv. A single space
e. A separator line
f. 5 or 6 lines that contain the days of that month:
i. Print exactly 30 days always (avoids leap-years etc).
ii. Separate day sections with pipes "|" in between
iii. Lay out the date numbers with the usual logic:
1. The first day of Junuary is specified with the argument FIRSTDAY
2. The first day of each other month is on the weekday following the last
weekday of the previous month
3. When a week is not “full” with dates, blank days are printed to maintain
spacing, both at the start and end of the month
g. Each non-empty day section must contain, in order:
i. A single space
ii. The date as a one or two digit integer, following correct ordering
iii. Additional spaces to pad up to DAYSIZE if the number was too short
iv. A single space
h. The final line of the year must be a separator line