lab02 - Odds and primes: Fun with arrays and makefiles

Collaboration policy

This lab must be completed individually (and not with a pair partner).

Getting setup with VS Code

You have the option of continuing to work with vim or try a new editor (VS Code).

Setting up VS Code for remote development is really useful because you can access your files on csil remotely through VS Code. It allows you to use a modern editor while working in the csil environment.

Use can use Samba to mount your CSIL directory so that it is accessible “as if” it were a hard drive connected to your computer. That allows you to run VS Code on your own machine, but access the files on CSIL. The articles below explain how, and have links to videos:

You’ll still need a terminal window on CSIL to run your code. You can use the VS Code terminal windows, but I encourage you to try having a separate terminal window; it is nice to have a whole window for your terminal screen, instead of just the tiny little one built into VS Code.

Step 0: Log on to CSIL and bring up a terminal window.

As a reminder, here’s how to get a terminal:

From	Get a terminal on CSIL by
Machines in Phelps 3525	Go to the Application Menu, then System Tools, then Terminal Window
Windows	Use Powershell, then `ssh username@csil.cs.ucsb.edu`
MacOS	Use Terminal, then `ssh username@csil.cs.ucsb.edu`
Unix/Linux	Use a terminal shell, then `ssh username@csil.cs.ucsb.edu`

For more information, see: https://ucsb-cs16.github.io/topics/ssh/

Step 1: Set default git branch

(If you already did this step during a previous lab, you may skip it; you only need to do it once.)

In October 2020, GitHub changed their default branch name from master to main.

To configure git (for your CSIL account) for this change, we can run the following command.

git config --global init.defaultBranch main

Step 2: Find your lab02-GITHUBID repo, and clone it into `~/cs16`

Use cd to move into your ~/cs16 directory.
Find the repo lab02-GITHUBID in the GitHub org for this course.
Copy the ssh URL for that github repo (it should start with git@github.com, not https)
Use git clone PASTE-SSH-URL-HERE to clone that repo into your ~/cs16 directory.

You may see this message; if so, that’s normal:
```
warning: You appear to have cloned an empty repository.
```
Use cd lab02-GITHUBID to move yourself into that directory.

Step 3: Add a remote for starter code and pull it in

We’ve explained git remotes in a few previous labs, so in this lab, I’ll only give the short version of the instructions. But be sure that you’ve read through the explanation of git remotes in previous labs, since it may show up on homework or exam questions about git remotes.

The starter code lives in this repo, which you can visit in a web browser to look at the starter code:

https://github.com/ucsb-cs16-w23/STARTER-lab02

To add a remote for this repo, we’ll use the ssh url, like this:

git remote add starter git@github.com:ucsb-cs16-w23/STARTER-lab02.git

To pull in the starter code, use:

git pull starter main

Then use an ls command, and you should see new files in your directory. That should look something like this:

$ ls
Makefile		arrayToStringTest.cpp	maxOfArray.cpp		minOfArrayTest.cpp	tddFuncs.cpp
README.md		countEvens.cpp		maxOfArrayErrorTest.cpp	sumOdds.cpp		tddFuncs.h
arrayBoundsDemo.cpp	countEvensTest.cpp	maxOfArrayTest.cpp	sumOddsTest.cpp		utility.cpp
arrayFuncs.h		countPrimes.cpp		minOfArray.cpp		sumOfArray.cpp		utility.h
arrayToString.cpp	countPrimesTest.cpp	minOfArrayErrorTest.cpp	sumOfArrayTest.cpp	utilityTest.cpp
$ 

With these files in place, you are ready to start coding.

If you don’t see those files, go back through the instructions and make sure you didn’t miss a step.

Step 4: Reviewing Separate Compilation

The files in your directory this week use separate compilation, that is each program is not necessarily taking all of its code from a single .cpp source file.

In Lecture on 02.16, we introduced the idea of separate compilation, where your C++ program may be divided among multiple source files. The following web page explains more about separate compilation, dividing your program up among multiple C++ and .h files, and using a Makefile. I strongly encourage you to read over it briefly before you proceed with the lab: Separate Compilation and Makefiles

Step 5: Writing isOdd(), isEven() and isPrime()

Your first step is very simple to describe, but somewhat challenging. The challenge here is mostly C++ coding — we will not get into the details of the separate compilation until a bit later.

To get started, do the following steps:

Step 5a: make clean

In your working directory, type ls and make note of the different files therein: some are .cpp types, some are .o (short for “object file”), some are .h (short for “header file”), and others do not have extensions (they are binary executables). Now, type make clean. This command cleans out any .o files and executables from your directory

That should look like this:

-bash-4.2$ make clean
/bin/rm -f arrayToStringTest arrayBoundsDemo countEvensTest minOfArrayTest minOfArrayErrorTest
countPrimesTest maxOfArrayTest maxOfArrayErrorTest sumOddsTest sumOfArrayTest utilityTest *.o

-bash-4.2$

Take a look in the Makefile file to understand why this happened.

Step 5b: make utilityTest

This command makes the executable for a main program, defined in utilityTest.cpp, that tests the functions defined in utility.cpp. Recall that for functions defined in a file such as utility.cpp that has no main(), the function prototypes are defined in the file utility.h Look at the source code for both utility.cpp and utility.h to see what they contain. Recall that a “stub” is place-holder code that allows an incomplete function to compile. It is designed to fail all the tests, though for a boolean function, since there are only two possible values (true and false), any stub value you choose is going to pass at least some of the tests.

That should look like this:

-bash-4.2$ make utilityTest
g++ -Wall -Wno-uninitialized   -c -o utilityTest.o utilityTest.cpp
g++ -Wall -Wno-uninitialized   -c -o tddFuncs.o tddFuncs.cpp
g++ -Wall -Wno-uninitialized   -c -o utility.o utility.cpp
g++ -Wall -Wno-uninitialized  utilityTest.o tddFuncs.o utility.o -o utilityTest

-bash-4.2$

Step 5c: Run ./utilityTest

Next, type ./utilityTest

This runs the utilityTest program that tests the three functions isOdd, isEven and isPrime. As we noted above, some of the tests will pass, even though the implementation of the three functions is totally bogus (hard coded to return false always).

Here is what that looks like (some output truncated)

-bash-4.2$ ./utilityTest
	FAILED: isEven(2)
		Expected: 1 Actual: 0
PASSED: isEven(3)
	FAILED: isEven(4)
		Expected: 1 Actual: 0
PASSED: isEven(55)

[...      Some output omitted here... ]

PASSED: isPrime(64507)
	FAILED: isPrime(69997)
		Expected: 1 Actual: 0
PASSED: isPrime(-55)
PASSED: isPrime(-80)
PASSED: isPrime(0)
PASSED: isPrime(1)

-bash-4.2$

Step 5d: Repeat: edit, compile, run, until all tests pass

Now do these steps, repeatedly, until all tests pass:

edit utility.cpp
make utilityTest
run utilityTest (e.g. ./utilityTest)

Submit working versions of your code on github using the commands:

git add *.cpp *.h
git commit -m "implemented utility function - nameof function()"
git push origin main

You must only proceed with the rest of the lab once you have implemented all the utility functions and pass the provided test cases. This is because for other files that you will be editing later, you will NEED functions isOdd, isEven and isPrime. Once you get them working, you will be able to call them in other files and KNOW that they work properly. You will not have to rewrite the function definition.

When all the tests for utlityTest pass, do a final push to github and move on to the next step.

Step 6: Reviewing the rest of the files and what your tasks are<

Now, let us look at the files you actually have in your directory, and what you need to do with them. You have the following .cpp files. This table indicates what you must do with each one to get full credit on this lab.

Filename	Your task	Details
arrayBoundsDemo.cpp	NOTHING TO CHANGE OR SUBMIT.	This is here as example code only. You are encouraged to run it, study it, and learn about how array bounds work in C++
arrayToString.cpp	NOTHING TO CHANGE OR SUBMIT.	This code is part of your solution, but you do not have to submit it - we will use our own version, which matches the one in your sample directory. This file just has utiltiy funcitons for printing arrays as strings.
arrayToStringTest.cpp	NOTHING TO CHANGE OR SUBMIT.	This code is part of your solution, but you do not have to submit it - we will use our own version, which matches the one in your sample directory. This file is an example of how to test cases to determine whether the output of `arrayToString` works correctly.
countEvens.cpp	REPLACE STUB WITH CORRECT CODE.	You must replace the code in this file with correct code that returns the number of even integers in each array passed in.
countEvensTest.cpp	NO MODIFICATIONS NEEDED	This tests the changes you made in countEvens.cpp.
countPrimes.cpp	REPLACE STUB WITH CORRECT CODE.	You must replace the code in this file with correct code that returns the number of prime integers in each array passed in. Treat negative numbers, 0 and 1 as “not prime”. You may want to add a definition of `isPrime()` to the utility.cpp file and a function prototype to utility.h so that you can call function `isPrime` in your solution.
countPrimesTest.cpp	NO MODIFICATIONS NEEDED	This tests the changes you made in countEvens.cpp.
maxOfArray.cpp	REPLACE STUB WITH CORRECT CODE.	You can look at minOfArray.cpp for hints. This one should be easy.
maxOfArrayErrorTest.cpp	REPLACE EMPTY MAIN WITH TESTS.	Insert code to call maxOfArray with zero length array. Use minOfArrayErrorTest.cpp as a model.
maxOfArrayTest.cpp	REPLACE EMPTY MAIN WITH TESTS.	Insert code to call `assertEqual` exactly seven times testing whether `maxOfArray` returns correct values. Use minOfArrayTest.cpp as a model. It must be exactly “seven” calls to `assertEquals` to pass the Gradescope tests. You should call your arrays the same things that they are called in `minOfArrayTests`, and the lengths should be the same. So the messages you get out for passed tests should match the messages from `minOfArrayTests` except that the name of the function is `maxOfArray` instead of `minOfArray`. You MAY change the values in the arrays themselves, though, to make the tests better tests, if you need to. (Note that just hard coding a program that prints “PASSED” seven times with the apprpriate messages is not sufficient to get credit–you need to really have actual tests. Any attempt to “game the system”, i.e. to get Gradescope tests to pass without a bona-fide attempt to actually solve the problem will get zero credit.)
minOfArray.cpp	NOTHING TO CHANGE.	This is a model of correct code that can serve as a hint for how to write maxOfArray.cpp
minOfArrayErrorTest.cpp	NOTHING TO CHANGE.	This is an model of correct code for how to test whether a function behaves as expected when given input that should print a message to cerr and exit the progrm.
minOfArrayTest.cpp	NOTHING TO CHANGE.	This is a model of how to do unit testing on a function that returns an integer.
sumOdds.cpp	REPLACE STUB WITH CORRECT CODE.	You must replace the code in this file with correct code that returns the number of sum of the odd integers in each array passed in. Negative odd integers count as odd integers.
sumOddsTest.cpp	REPLACE EMPTY MAIN WITH TESTS	Insert code to call `assertEqual` exactly seven times testing whether `sumOdds` returns correct values. Use sumOfArrayTest.cpp as a model. It must be exactly “seven” calls to `assertEquals` to pass the Gradescope tests. You should call your arrays the same things that they are called in `sumOfArrayTests`, and the lengths should be the same. So the messages you get out for passed tests should match the messages from `sumOfArrayTests` except that the name of the function tested is `sumOdds` instead of `sumOfArray`. You MAY change the values in the arrays themselves, though, to make the tests better tests, if you need to. (Note that just hard coding a program that prints “PASSED” seven times with the apprpriate messages is not sufficient to get credit–you need to really have actual tests. Any attempt to “game the system”, i.e. to get Gradescope tests to pass without a bona-fide attempt to actually solve the problem will get zero credit.)
sumOfArray.cpp	INCORRECT CODE FOR YOU TO FIX.	The sum is not initialized properly. So the tests should fail. Your job is to see that the tests fail, then fix the sum initialization so the tests pass. Should be easy.
sumOfArrayTest.cpp	NOTHING TO CHANGE.	This is a set of tests to verify whether `sumOfArray()` works correctly.
tddFuncs.cpp	NOTHING TO CHANGE.	These are two functions that can be used to test functions that return either int or string values.
utility.cpp	ADD FUNCTIONS HERE AS NEEDED.	If you need to write your own helper functions, e.g. `isPrime`, `isOdd`, `isEven`, to use in other files, here is where you can put those definitions.

Step 7: Actually Getting Started

I suggest you start by typing: make

You should see a lot of activity as programs are compiled. You then will have a lot of executables you can run. Here is a list. Try running each one and see what happens.

Note these are the programs listed under BINARIES in the Makefile.

file	Anything to do?	explanation
arrayToStringTest	no	Run this and all tests should pass. Nothing to do here.
arrayBoundsDemo	no	Run this, and look at the code. This is an opportunity to learn something about how we pass arrays to functions in C++, but there is nothing you have to turn in from this program for the lab. It is just here as an example for you to learn from.
countEvensTest	*YES*	Run this, and you will see all the tests fail. YOU NEED TO FIX THE `countEvens` function and then get all these tests to pass.
minOfArrayTest	no	Just run this and see the tests pass. You can use the .cpp file minOfArrayTest.cpp as a model for writing maxOfArrayTest.cpp
minOfArrayErrorTest	no	Just run this and see the output. It should be `ERROR: minOfArray called with size < 1` printed on cerr (the standard error output stream). The Gradescope system will check this as one of the acceptance tests for this lab, and it will also check that `maxOfArrayErrorTest` does the same thing. You can use the .cpp file minOfArrayErrorTest.cpp as a model for writing maxOfArrayErrorTest.cpp
countPrimesTest	*YES*	Run this, and you will see all the tests fail. YOU NEED TO FIX THE `countPrimes` function and then get all these tests to pass.
maxOfArrayTest	*YES*	Run this, and you will see that initially there is no output. That is because the main is empty. YOU NEED TO REPLACE THIS MAIN with code that tests `maxOfArray`. Use `minOfArrayTest` as a model. Initially, just put in the tests, and keep `maxOfArray` returning the stub vaue -42. See all the tests fail. Then get `maxOfArray` to return the right values and see all the tests pass.
maxOfArrayErrorTest	*YES*	Run this, and you will see that initially there is no output. That is because the main() is empty. YOU NEED TO REPLACE THIS MAIN with code that tests `maxOfArray`. Use `minOfArrayTest` as a model. Initially, just put in the tests, and keep `maxOfArray` returning the stub vaue -42. See all the tests fail. Then get `maxOfArray` to return the right values and see all the tests pass.
sumOddsTest	*YES*	Run this, and you will see that initially there is no output. That is because the main() is empty. YOU NEED TO REPLACE THIS MAIN with code that tests `sumOdds`. Use `minOfArrayTest` as a model. Initially, just put in the tests, and keep `sumOdds` returning the stub vaue -42. See all the tests fail. Then get `sumOdds` to return the right values and see all the tests pass.
sumOfArrayTest	*YES*	Run `sumOfArrayTest` and you will see that all the tests fail. Getting them to pass is probably the easiest step in this lab. Just look at the `sumOfArray` function, which is almost correct - it just needs you to initialize sum correctly. Note that in C/C++ variables are NOT automatically initialized, and failing to initialize them does not always result in an error message or warning unless you specifically ask the compiler to tell you about those. For this lab, the Makefile deliberarly turns that warning OFF so that we have to catch that ourselves.

So, if you go through that list, and do all the things indicated, you are finished with the lab and ready to submit.

Step 8: Checking your work before submitting

When you are finished, you should be able to type make tests and see the following output:

-bash-4.2$ make tests
./arrayToStringTest
PASSED: arrayToString(fiveThrees,5)
PASSED: arrayToString(zeros,3)
PASSED: arrayToString(empty,0)
PASSED: arrayToString(primes,10)
PASSED: arrayToString(meaning,1)
PASSED: arrayToString(mix,10)
./countEvensTest
PASSED: countEvens(fiveThrees,5)
PASSED: countEvens(zeros,3)
PASSED: countEvens(fiveInts,5)
PASSED: countEvens(empty,0)
PASSED: countEvens(primes,10)
PASSED: countEvens(meaning,1)
PASSED: countEvens(mix,10)
./countPrimesTest
PASSED: countPrimes(fiveThrees,5)
PASSED: countPrimes(zeros,3)
PASSED: countPrimes(fiveInts,5)
PASSED: countPrimes(empty,0)
PASSED: countPrimes(primes,10)
PASSED: countPrimes(meaning,1)
PASSED: countPrimes(mix,10)
./maxOfArrayTest
PASSED: maxOfArray(fiveThrees,5)
PASSED: maxOfArray(zeros,3)
PASSED: maxOfArray(fiveInts,5)
PASSED: maxOfArray(fiveInts,2)
PASSED: maxOfArray(fiveInts,3)
PASSED: maxOfArray(meaning,1)
PASSED: maxOfArray(mix,10)
./minOfArrayTest
PASSED: minOfArray(fiveThrees,5)
PASSED: minOfArray(zeros,3)
PASSED: minOfArray(fiveInts,5)
PASSED: minOfArray(fiveInts,2)
PASSED: minOfArray(fiveInts,3)
PASSED: minOfArray(meaning,1)
PASSED: minOfArray(mix,10)
./sumOddsTest
PASSED: sumOdds(fiveThrees,5)
PASSED: sumOdds(zeros,3)
PASSED: sumOdds(fiveInts,5)
PASSED: sumOdds(fiveInts,3)
PASSED: sumOdds(fiveInts,2)
PASSED: sumOdds(meaning,1)
PASSED: sumOdds(mix,10)
./sumOfArrayTest
PASSED: sumOfArray(fiveThrees,5)
PASSED: sumOfArray(zeros,3)
PASSED: sumOfArray(fiveInts,5)
PASSED: sumOfArray(fiveInts,3)
PASSED: sumOfArray(fiveInts,2)
PASSED: sumOfArray(meaning,1)
PASSED: sumOfArray(mix,10)
./utilityTest
PASSED: isEven(2)
PASSED: isEven(3)
PASSED: isEven(4)
PASSED: isEven(55)
PASSED: isEven(-55)
PASSED: isEven(-80)
PASSED: isOdd(2)
PASSED: isOdd(3)
PASSED: isOdd(4)
PASSED: isOdd(55)
PASSED: isOdd(-55)
PASSED: isOdd(-80)
PASSED: isPrime(2)
PASSED: isPrime(3)
PASSED: isPrime(4)
PASSED: isPrime(55)
PASSED: isPrime(859)
PASSED: isPrime(861)
PASSED: isPrime(863)
PASSED: isPrime(1337)
PASSED: isPrime(1373)
PASSED: isPrime(64507)
PASSED: isPrime(69997)
PASSED: isPrime(-55)
PASSED: isPrime(-80)
PASSED: isPrime(0)
PASSED: isPrime(1)

-bash-4.2$

And, you should be able to type make errorTests and see the following output:

-bash-4.2$ make errorTests
./minOfArrayErrorTest
ERROR: minOfArray called with size < 1
make: [errorTests] Error 1 (ignored)
./maxOfArrayErrorTest
ERROR: maxOfArray called with size < 1
make: [errorTests] Error 1 (ignored)

-bash-4.2$

At that point, you are ready to try submitting on the Gradescope system.

Step 9: Turn in your code on Gradescope

Navigate to the directory containing your code for this week’s lab.
Use the ls command to list your files and to be sure that you have all .cpp files (that you received as starter files) in your directory. It is ok if there are other files ( *.txt, *.o, etc.) along with the executables. You only have to submit *.cpp files

-bash-4.2$ cd ~/cs16/lab02_jgaucho

-bash-4.2$ ls
arrayBoundsDemo.cpp    maxOfArray.cpp           sumOfArray.cpp
arrayFuncs.h           maxOfArrayErrorTest.cpp  sumOfArrayTest.cpp
arrayToString.cpp      maxOfArrayTest.cpp       tddFuncs.cpp
arrayToStringTest.cpp  minOfArray.cpp           tddFuncs.h
countEvens.cpp         minOfArrayErrorTest.cpp  utility.cpp
countEvensTest.cpp     minOfArrayTest.cpp       utility.h
countPrimes.cpp        README.md                utilityTest
countPrimesTest.cpp    sumOdds.cpp              utilityTest.cpp
Makefile               sumOddsTest.cpp
-bash-4.2$

Use git add *.cpp to add all of the .cpp files to your next commit
Use git status to see if any other files have been modified and need to be updated
Use git commit -m “code for lab02” to make a commit with all of these files
Use git push origin main to update your files on GitHub

Check on the GitHub webpage for the course organization (https://github.com/ucsb-cs16-w23) to find your repo for this lab and make sure that it contains the up-to-date version of your code.

Then go to Gradescope and submit all of your files from your GitHub repo.

Check that you have a correct score
Also check that you have followed these style guidelines:

Indentation is neat, consistent and follows good practice (see below)
Variable name choice: variables should have sensible names. More on indentation: Your code should be indented neatly. Code that is inside braces should be indented, and code that is at the same “level” of nesting inside braces should be indented in a consistent way. Follow the examples from lecture, the sample code, and from the textbook.