Computer Science 352 Programming Assignment 1 solution

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This first PA for CS 352 has three parts. The first will require you to research, experiment with, and write
several bash commands. The second will be a very simple C program. The Third will require you to write
python code to test an executable (compiled from C) using the os and subprocess python modules. For the
project, you should end up with the following directory structure:
pa1
├── pythagorean
│ └── pythagorean.c
├── sbt
│ └── sbt.py
└── shell
└── commands.txt
Part A – Bash Commands
You should write a bash command for each of the descriptions shown in this section, and put each in the file
commands.txt. You should format it as follows:
(1)
first_command
(2)
second_command
. . . .
For part A, you may only use the following commands:
cd ls mkdir touch cat grep cut uniq wc cal find sort head tail tr
You may (and should) also use pipes, redirection, and semicolons. If you are unsure how any of these work,
use the man pages. Each command should be a one-liner.
1. A bash command to show the relative paths for every .py, .c, and .java file within the current working
directory or any of its subtrees. The python files should display first, then the c files, then the java files.
For example, say that you are currently in a directory named test with the following structure within it:
└── test
├── code
│ ├── something.ml
│ └── something.py
├── other
│ ├── calculate.c
│ └── compute.java
└── scripting.py
If you were to run your command, you should see the following result:
$ your_command
./scripting.py
./code/something.py
./other/calculate.c
./other/compute.java
2. A bash command to search through words within the standard /usr/share/dict/words unix file. The
command should determine how many unique “words” are in the file if only the first four characters of
each word on each line is used. For example, lets say that /usr/share/dict/words had only these
four words in it:
antelope
tarantula
antenna
taraplaza
If we were to run the command, we should get a result of 2.
If we only include the first 4 letters, there are only two unique words (ante and tara).
$ your_command
2
3. A bash command that displays the numbers of the julian-calendar days for 2022 for Sunday. Recall that
in a julian calendar, days are numbered 1-365, rather than resetting back to 1 each month. The results
should be sorted numerically. In total you should get 52 numbers, but since that is long I will show you a
truncated version of the output you should expect:
$ your_command
2
9
16
23
. . . .
338
345
352
359
4. A command to get a list of the unique creation months of the files in the current working directory. No
two month names should appear twice, even if there are multiple files with that creation month. You can
use ls -o to show a list of the files with the creation months (and other things) included. Thus, for
example, say we ran an ls -o within a directory and got these results:
drwx—— 20 userA 52 Dec 9 21:33 somefile.c
drwx—— 23 benjamin 53 Dec 9 12:53 runthis.py
drwx—— 96 userB 161 Jan 3 16:01 something.js
drwx—— 14 userA 25 Dec 7 18:42 numberzz.csv
If we were to run our command, we should get:
$ your_command
Dec
Jan
Part B – Super Simple C Program
In part B, you are tasked with writing a very simple C program. You will be writing much larger and more
complex C programs later on in the course, but for now we are starting with something very simple. You should
write a C program that uses the pythagorean theorem to determine the length of the hypotenuse of a right
triangle, given the length of the other two sides. When using the pythagorean theorem, we generally refer to
the hypotenuse as side C, and the other two sides as sides A and B.
The program should read in the lengths of sides A and B as integer values. It should determine the length of
side C and store it as a double. It should then print out this value and then exit with a status code of 0. You
should write this code in a file named pythagorean.c located in the directory shown in this PAs overview.
Remember, both for this PA and for every future PA, you should compile using gcc and with the flags -Wall
-Werror -std=c11. Two examples are shown below, with input values typed by the user highlighted in red.
Your program should match the input and output formatting exactly.
$ gcc -Wall -Werror -std=c11 pythagorean.c
$ ./a.out
Enter side A length:
3
Enter side B length:
4
Length of side C: 5.00
$ ./a.out
Enter side A length:
125
Enter side B length:
81
Length of side C: 148.95
Part C – An Executable Tester in Python
In part C (the final part of the assignment) you will be writing a program in python for testing if executables are
compiling and running correctly. For this particular PA, you should use it to test out the pythagorean.c program.
In future assignments, you can re-use this program to test out other PAs. You are also welcome to add
additional features to it in the future, though for the purpose of this PA you should stick to only the features
described in the spec.
The program you will write should be named sbt.py (Super Basic Tester) and should be located in the sbt
directory within the pa1 directory, as indicated in the assignment summary.
This program should accept two input values via standard input. The first will be the path / name of the .c file
that it will be testing. The second will be the path / name to a directory containing test cases for the program.
Your program should expect that the test directory will have the following structure:
─── test_directory
├── test-A
│ ├── input.txt
│ └── output.txt
├── test-B
│ ├── input.txt
│ └── output.txt
. . . .
The test directory should contain 0 or more directories within it, with names that correspond to what the “name”
of that particular test. Each of these directories should have exactly two files within it named input.txt and
output.txt. input.txt should contain whatever content you want to be sent as the standard input to the
program being tested for this case. output.txt should contain the exact test that you expect your program to
produce, given the corresponding standard input from input.txt.
The outline of what this python program should do is as follows:
1. Ask the user for the two input values (.c file name and test directory)
2. Run a command to compile the .c program ( gcc -Wall -Werror -stc=c11 FILE.c )
3. If the compilation failed for any reason, print “failed to compile your code” and then exit.
4. If it worked, loop through each of the directories within the test directory folder
5. For each one:
a. Run the executable and give it the standard input text from input.txt
b. Store / save what it prints to standard output
c. Compare the result with the contents of the output.txt file
d. If the same, print “#### Test: DIR_NAME passed! ####”
e. If different, print “#### Test: DIR_NAME failed! ####” and then print out a
comparison of the results.
You should already be familiar with programming in python, however there will be some aspects of this that you
might not have done before. In particular, at this point in your coding career, you may not have ever done the
following within python:
● Looped through ever directory within a directory
● Run a shell command from python, and checked the result
Both of these are possible though! For the former, I recommend that you use the os module, in particular the
os.listdir function. For the latter, you should use the subprocess module, in particular subprocess.Popen
and subprocess.check_output functions. The subprocess module gives you the ability to run a shell / bash
command from python and fetch what the command printed out. You can read more about this module on yht
python docs website: https://docs.python.org/3/library/subprocess.html.
Let’s walk through an example to see how this program should behave. We will use pythagorean.c as our
program to test.
First off, say we have started working on pythagorean.c, but it is not finished and there is a syntax error in the
code. If we try to run the tester on this program that has a syntax error, it should beehive in the following way:
$ python3 sbt.py
C source file path: ./pythagorean.c
Test file directory path: ./tests
failed to compile your code
$
Now say we spend some more time working on pythagorean.c so that there are no longer any syntax or
compilation problems, though we are still unsure if it actually produces the correct answer. In order to test this,
we will create a test directory that contains two test cases:
─── tests
├── area-3-4
│ ├── input.txt
│ └── output.txt
└── area-7-2
├── input.txt
└── output.txt
Each of the .txt files have the following contents.
area-3-4/input.txt area-3-4/output.txt area-7-2/input.txt area-7-2/output.txt
3
4
Enter side A length:
Enter side B length:
Length of side C: 5.00
7
2
Enter side A length:
Enter side B length:
Length of side C: 7.28
Notice how in the output.txt files, the numbers that the user would type as input are not included. Now, we
go to test again!
$ python3 sbt.py
C source file path: ./pythagorean.c
Test file directory path: ./tests
#### Test: area-3-4 passed! ####
#### Test: area-7-2 failed! ####
#### EXPECTED TO SEE:
Enter side A length:
Enter side B length:
Length of side C: 7.28
#### INSTEAD GOT:
Enter side A length:
Enter side B length:
Length of side C: 7.280110
$
Notice that the area-3-4 test case passed! However, the other one failed, due to the expected output having
less decimal places printed out. If we went in and fixed the program and then ran again, we should see:
$ python3 sbt.py
C source file path: ./pythagorean.c
Test file directory path: ./tests
#### Test: area-3-4 passed! ####
#### Test: area-7-2 passed! ####
$
You should come up with a few tests of your own, in addition to the ones shown here in the spec, and ensure
your program passes each one.
Submitting Your PA
After you have completed the three parts of this PA, double check that the file structure and file / directory
names match what is shown in the project overview on the first page. You are welcome to include your test
cases within the sbt or pythagorean directories as well if you want. Also, before you submit, you should ensure
that your bash scripts, C program, and SBT compile / run correctly on lectura, not just your own computer.
Once you are ready to submit, zip up the pa1 directory by running:
$ zip -r pa1.zip ./pa1
Then, turn this file to the PA 1 dropbox on gradescope.