University of California, Santa Barbara
Dept. of Computer Science
Lab 05: Selection Sort
Assigned:
Due:
Points:
Monday, May 6, 2024
Monday, May 13, 2024
100
Table of Contents
Goals of the Lab Assignment ................................................................................................................... 1
STEP 0: Getting Started ........................................................................................................................... 1
STEP 1: Copying some programs ............................................................................................................. 2
STEP 2: Understanding the starter code and inheritance hierarchy ........................................................ 3
STEP 3: Implement the files to pass your tests ........................................................................................ 3
STEP 4: Testing ........................................................................................................................................ 5
STEP 5: Submitting via Gradescope ......................................................................................................... 5
Goals of the Lab Assignment
By the time you have finished this lab, you should have demonstrated your ability to code a selection sort on an
array of pointers to objects in C++. You will also get more practice with doing test-driven development of
object-oriented C++ code.
STEP 0: Getting Started
This lab may be done solo, or in pairs.
Before you begin working on the lab, please decide if you will work solo or with a partner.
As stated in previous labs, there are a few requirements you must follow if you decide to work with a partner:
•
Your partner must be enrolled in the same lab section as you.
•
You and your partner must agree to work together outside of lab section in case you do not finish the lab
during your lab section. You must agree to reserve at least two hours outside of lab section to work
together if needed. You are responsible for exchanging contact information in case you need to reach
your partner.
•
If you choose to work with a partner for a future lab where pair programming is allowed, then you must
choose a partner you have not worked with before.
•
You MUST add your partner on Gradescope when submitting your work EACH TIME you submit a
file(s). After uploading your file(s) on Gradescope, there is a “Group Members” link at the bottom (or
“Add Group Member” under “Groups”) where you can select the partner you are working with.
Whoever uploaded the submission must make sure your partner is part of your Group. Click on “Group
Members” -> “Add Member” and select your partner from the list.
•
You must write your Name(s) and Perm number on each file submitted to Gradescope.
•
Once you and your partner are in agreement, choose an initial driver and navigator, and have the driver
log into their account.
MATNI
CS 32, Spring 2024
Page 1 of 5
University of California, Santa Barbara
Dept. of Computer Science
STEP 1: Copying some programs AND integrating git into your workflow
In this step, we are going to copy the lab05 starter files from the instructor’s directory into your /cs32/lab05
directory.
The files are in the instructor’s directory at: ~zmatni/public_html/cs32/labs/lab05/*
and also accessible via the URL: http://cs.ucsb.edu/~zmatni/cs32/labs/lab05/
You want to copy these files into your ~/cs32/lab05 directory, which you should know how to do by now.
You should now see several files in your directory. If so, you are ready to move on. If you don’t see those files,
go back through the instructions and make sure you didn’t miss a step. If you still have trouble, ask your TA /
tutors for assistance.
It’s now time to use the git-command line tools to perform version control for the files in your git repo. The four
essential commands we will be using are:
git pull
git add .
git commit -m "Initial version of lab05 files"
git push origin master
Go ahead and type them out on a terminal in your git repo directory. The above commands save a snapshot of
your code on GitHub. To check that this was done successfully, open a web-browser and navigate to your repo
on GitHub. Then check to see that the starter code appears in your repo.
Note: Every time you add a new piece of logic to your code, you should save a snapshot of the latest version of
your code by issuing the commands: git add … , git commit … and git push …
All the previous versions will be available to you as well and you have the option of reverting to older versions
(we will see how in later labs). As you go through the rest of this lab you will essentially need to use these
commands to keep track of the different versions of your code. Note that you should only keep relevant files
in your repo - avoid uploading non-important LARGE files in your repo since this may cause errors when
making your submission to Gradescope.
Congratulations on integrating git into your workflow!
MATNI
CS 32, Spring 2024
Page 2 of 5
University of California, Santa Barbara
Dept. of Computer Science
STEP 2: Understanding the starter code
STEP 2a: Understanding the tddFuncs.cpp code
You may find it interesting to compare the versions of tddFuncs.h and tddFuncs.cpp from with the ones
from this lab (lab05).
You do NOT need to make any changes to these files. However, they serve the purpose of showing how we can
use Template Functions in C++ and Template Specialization to create code that is more “DRY”, i.e. follows
the adage “Don’t Repeat Yourself”.
Here are links to the versions of these files from lab01 and this week:
lab01
lab05
tddFuncs.h
tddFuncs.h
tddFuncs.cpp
tddFuncs.cpp
Some things to note:
•
In the lab01 version of tddFuncs.cpp, there was duplicated code—identical versions of
assertEquals for both int and std::string. In the lab05 version, this has been DRY’ed up and
factored out into a template in the lab05 tddFuncs.h.
•
In the lab05 version of tddFuncs.cpp, there are also two overloaded versions of the function
assertEquals that are NOT using the template. These versions of the function are needed because Cstrings (i.e. const char * and const char * const values) cannot be compared with the ==
operator. The version for two C-strings used strcmp instead, while the version for a C-string and an
std::string simply converts the C-string to a C++ string and invokes the template version for
std::string.
Again, you don’t need to do anything with this for this lab, so if you want to gloss over this for now and come
back to it later, that’s fine. You need to look it over though, and understand what is going on.
A final note: the way we overloaded the functions here does work, and it has the advantage of being easy to
understand and follow. However, it is probably NOT the “current best practice” way of handing this, and strictly
speaking, is not “template specialization”, it is rather just “garden variety overloading”. We’ll go over the
“better way”, i.e. true template specialization, in a future lab or lecture. For now, if you are curious, and want to
“read ahead”, consider the following StackOverflow link:
http://stackoverflow.com/questions/17344405/template-function-specialization-vs-overloading
(H/T to Hunter Laux for finding this.)
MATNI
CS 32, Spring 2024
Page 3 of 5
University of California, Santa Barbara
Dept. of Computer Science
STEP 2b: Understanding the CXXFLAGS in the Makefile
In this week’s Makefile, as with last weeks, we have the following.
CXXFLAGS = -Wall -Wextra -Wno-unused-parameter -Wno-unused-private-field
# Change to this before final submission:
# CXXFLAGS = -Wall -Wextra -Werror
See the explanation in lab01 of these two definitons for CXXFLAGS. It will be important for you to modify these
before submitting to make sure that your code will compile with those flags set.
STEP 2c: Understanding the Student and Roster classes
The Student.h and Student.cpp classes are mostly unchanged from lab01, except for the addition of a few
new methods.
Please look those over—these are mostly methods for reading in a Student from a comma-separated string, and
are there so that we can read in students from a CSV file (i.e. a file of comma separated values) into a Roster.
The Roster.h and Roster.cpp files, though, are new.
You’ll see that the Roster.h file contains the specification of a class that represents a collection of Students. It
represents this collection with a simple fixed size C++ array of pointers to Student objects. THERE ARE
CERTAINLY BETTER WAYS TO IMPLEMENT A COLLECTION OF STUDENTS. The point for this
week’s lab, though, is to understand sorting algorithms.
We will implement a selection sort on the array of pointers to Student objects. Since we only have to swap the
pointers in the array—we don’t have to swap the entire Student object—our algorithm will run in the same
amount of time no matter how large the actual Student objects may be. In general, this is a good idea if/when
one is working with large objects.
The files where you will be making changes this week are:
• Student.cpp, where you’ll be updating the methods that you wrote in lab01. Don’t just copy over the entire
file though, because if you do, you’ll lose the new methods that we supplied you with in the starting point code.
• Roster.cpp, where you’ll be replacing stubs with correct code.
STEP 2d: Understanding the tests: testStudent.cpp and tddFuncs.cpp
What you should do next is to look through the test cases in testStudent.cpp (which includes all the tests
from the three test files in lab01) and testRoster1.cpp, testRoster2.cpp and testRoster3.cpp
Look over these files and understand how they work. Then, type make tests to compile and run all of the
tests.
You can also type, for example, make testRoster1 and ./testRoster1 to make and run these tests one at
a time.
MATNI
CS 32, Spring 2024
Page 4 of 5
University of California, Santa Barbara
Dept. of Computer Science
STEP 3: Make all the test cases pass
When you are ready, start editing Student.cpp, replacing the stubs for the constructor first, and then each of
the stubs for the other functions. Get all the tests in testStudent to pass first.
Then, read through testRoster1.cpp and see what methods in Roster.cpp you think you need to update in
order to get those tests to pass.
Then proceed to do the same with testRoster2.cpp and testRoster3.cpp.
STEP 4: Check your work before submitting
When you are finished, you should be able to type make clean and then make tests and see that all the test
cases pass.
At that point, you are ready to try submitting to the Gradescope system.
STEP 5: Submitting via Gradescope
The lab assignment “Lab05” should appear in your Gradescope dashboard in CMPSC 32. If you haven’t
submitted anything for this assignment yet, Gradescope will prompt you to upload your files.
For this lab, you will need to upload JUST your modified files (i.e. Student.cpp and Roster.cpp). For this
lab you are required to submit your files with your GitHub repo.
If you already submitted something on Gradescope, it will take you to their “Autograder Results” page. There
is a “Resubmit” button on the bottom right that will allow you to update the files for your submission. For this
lab, if everything is correct, you’ll see a successful submission passing all of the autograder tests.
Remember to add your partner to Groups Members for this submission on Gradescope if applicable. At
this point, if you worked in a pair, it is a good idea for both partners to log into Gradescope and check if
you can see the uploaded files for Lab05.
Acknowledgements
Some material in this lab is based on work originally written by Richert Wang.
MATNI
CS 32, Spring 2024
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