Last Updated: 2021-09-28 Tue 15:18
CSCI 2021 Project 1: C Programming
Due: 11:59pm Mon 10/04/2021
Approximately 4.0% of total grade
Submit to Gradescope (Submission Now Open)
Projects are individual work: no collaboration with other students is allowed. Seek help from course staff if you get stuck
for too long.
CODE DISTRIBUTION: p1-code.zip
VIDEO OVERVIEW: Canvas – Week 3 Videos
CHANGELOG:
Tue Sep 28 03:11:49 PM CDT 2021
A bug in the test cases for Problem 2 has been reported and corrected. This bug affects several tests for stock_plot()
where correct code would not pass tests. To patch the tests, download new versions of the following two files and copy them
into your project directory:
test_stock2.org
test_stock_funcs.c
All students will need to do this in order to pass the tests. The Gradescope autograder has been updated with these fixes as
has the p1-code.zip codepack. Thanks to the student who brought this to our attention.
Mon Sep 27 12:54:59 PM CDT 2021
The submission link for Project 1 is now open on Gradescope.
Fri Sep 24 04:21:44 PM CDT 2021
Added a link to the project overview video on Canvas and fixed the broken images for the Gradescope upload instructions.
Tue Sep 21 04:25:26 PM CDT 2021
The file stock.h had a few comments that have been removed. These were discarded fields in the stock_t type and an
incorrect comment mentioning a hashset. They do not affect any other parts of the project but have been removed to
reduce confusion such as what appeared in Post 41.
Table of Contents
1. Introduction
1.1. Grading Criteria
1.2. Getting Started
2. Download Code and Setup
2.1. Makefile
2.2. Automated Tests
3. Problem 1: Stock Plotting
3.1. Overview and Demo
3.2. Outline of stock_funcs.c
3.3. Editing and Testing
3.4. Implementation Notes
3.5. Grading Criteria for Problem 1
4. Problem 2: Completing Stock Plot
4.1. Overview
4.2. Setting Min/Max Index
4.3. Best Buy/Sell Index
4.4. Stock Files
4.5. Counting Lines
4.6. Loading Stock Files
4.7. Plotting Stocks
4.8. Optional MAKEUP CREDIT
4.9. Grading Criteria for Problem 2
5. Problem 3: Tree Sets in C
5.1. Overview
5.2. treeset_main Demonstration
5.3. tree_funcs.c: tree functions
5.4. treeset_main.c: main function / application
5.5. Grading Criteria for Problem 3
https://www.gradescope.com/
https://www-users.cse.umn.edu/~kauffman/2021/p1-code.zip
https://canvas.umn.edu/courses/268633/pages/week-03-videos
https://www-users.cse.umn.edu/~kauffman/2021/test_stock2.org
https://www-users.cse.umn.edu/~kauffman/2021/test_stock_funcs.c
https://piazza.com/class/ksuvqq1tdpo2jx?cid=41
6. Project Submission
6.1. Submit to Gradescope
6.2. Late Policies
1 Introduction
Basic application programming in C is an essential step downward towards the lower levels of computing. This project explores
fundamental aspects of getting work done in C:
Dynamic memory management with malloc()/free()
Reading data from files in text format
Displaying information to the screen
Reading commands from users in interactive programs
Building data structures with C structs
The assignment is divided into several problems utilizing many of the above techniques.
Problem 1 implements a few simple function surrounding a struct representing stock prices.
Problem 2 builds on the previous routines to complete a stock plotting program.
Problem 3 builds a simple binary tree application which stores unique strings.
Problems 1 and 2 build on each other and are somewhat easier than Problem 3. Strong consider going in order on the Project to take
advantage of the structure in early problems before reaching the more open-ended final problem.
1.1 Grading Criteria
Credit for this assignment will be given based on two categories.
Manual Inspection Criteria (~50%): Each problem has a checklist of things that graders will look for. The checklist is in
the spec and often contains hints on what to do. Make sure you have a look at these.
Automated Testing (~50%): Each problem has tests associated with it along with instructions on how to run those tests
from the command line. Tests require that code compiles and runs according to the descriptions given so make sure you
verify that these work.
1.2 Getting Started
Take the following steps to get started
1. Download the code associated with the project linked at the top of the spec. Unzip it and examine some of the provided
code.
2. Examine the overview of the files provided listed in the Download and Setup section. This gives brief descriptions of files
that already exist and those that you must create.
3. Pick a problem and read. There is a lot of information and many examples provided for each problem. Reading this will
help you write the correct code earlier rather than later.
4. Ask questions: if its not clear how to proceed, put up a Piazza post or visit an office hour.
5. Get coding: don’t wait to start for too long as this will greatly increase your stress level an potentially result in late
submissions.
6. Familiarize yourself with the late submission policy for assignments so you are not caught off guard. No submissions will
be accepted more than 48 hours after the deadline.
2 Download Code and Setup
Download the code pack linked at the top of the page. Unzip this which will create a project folder. Create new files in this folder.
Ultimately you will re-zip this folder to submit it.
File State Notes
Makefile Provided Build file to compile all programs
stock_funcs.c EDIT Problem 1/2 functions to write
stock_demo.c Provided Problem 1/2 demo code to show some function invocations
stock_main.c Provided Problem 2 main function, do not edit
stock.h Provided Problem 1/2 header file
http://www-users.cs.umn.edu/~kauffman/2021/syllabus.html#sec-3-5
File State Notes
test_stock_funcs.c Testing Testing file for Problems 1 & 2
data/stock-ascending.txt Data Data files for problems 1 & 2
data/stock-valley.txt Data
data/stock-jagged.txt Data
… Data
treeset.h Provided Problem 3 header file
treeset_funcs.c CREATE Problem 3 functions to write
treeset_main.c CREATE Problem 3 main function to write
data/stranger-demo.script Data Problem 3 sample input scripts to main program
data/1.tree Data Problem 3 sample tree set save files
data/2.tree Data
data/big.tree Data
…
TESTING
testy Testing Test running script
test-results/ Testing Directory in which temporary testing files are written
test_stock1.org Testing Problem 1 tests
test_stock2.org Testing Problem 2 tests
test_treeset.org Testing Problem 3 tests
2.1 Makefile
A Makefile is provided as part of this project. Building programs in C is a bit tedious and most folks use build systems of which
make is the oldest. The instructions and dependencies to create programs are written in a Makefile which is then interpreted by
the make program which will run gcc and other commands to create programs.
Use this Makefile by issuing commands like make prob1
> make prob2 # build problem 2 main program
gcc -Wall -Wno-comment -Werror -g -c stock_main.c
gcc -Wall -Wno-comment -Werror -g -c stock_funcs.c
gcc -Wall -Wno-comment -Werror -g -o stock_main stock_main.o stock_funcs.o
> make clean # remove all programs/binary object files
rm -f stock_main stock_demo test_stock_funcs treeset_main *.o
> make prob3 # build problem 3 main program
gcc -Wall -Wno-comment -Werror -g -c treeset_main.c
gcc -Wall -Wno-comment -Werror -g -c treeset_funcs.c
gcc -Wall -Wno-comment -Werror -g -o treeset_main treeset_main.o treeset_funcs.o
> make clean # remove all programs/binary object files
rm -f stock_main stock_demo test_stock_funcs treeset_main *.o
> make # build all programs/objects for the assignment
gcc -Wall -Wno-comment -Werror -g -c stock_main.c
gcc -Wall -Wno-comment -Werror -g -c stock_funcs.c
You are not required to understand all that is in the Makefile (yet) but it is a very useful tool and may be worth your while to
inspect.
Running make help will provide a summary of the build/test commands present in the Makefile.
2.2 Automated Tests
Automated tests are included with the code distribution. These tests are known to work on lab machines only but in most cases
they should run identically in Linux environments such as the Windows subsystem for Linux or a virtual machine.
The provided Makefile allows automated tests to be run via calls like make test-prob1 to test Problem 1 and make
test-prob2 to test Problem 2. See the transcript below.
gcc -Wall -Wno-comment -Werror -g -o stock_main stock_main.o stock_funcs.o
gcc -Wall -Wno-comment -Werror -g -c stock_demo.c
gcc -Wall -Wno-comment -Werror -g -o stock_demo stock_demo.o stock_funcs.o
gcc -Wall -Wno-comment -Werror -g -o test_stock_funcs test_stock_funcs.c stock_fun
gcc -Wall -Wno-comment -Werror -g -c treeset_main.c
gcc -Wall -Wno-comment -Werror -g -c treeset_funcs.c
gcc -Wall -Wno-comment -Werror -g -o treeset_main treeset_main.o treeset_funcs.o
> make help
Typical usage is:
> make # build all programs
> make clean # remove all compiled items
> make zip # create a zip file for submission
> make prob1 # built targets associated with problem 1
> make test # run all tests
> make test-prob2 # run test for problem 2
> make test-prob2 testnum=5 # run problem 2 test #5 only
>> make test-prob1 # run tests for problem 1, compiles required code
gcc -Wall -Wno-comment -Werror -g -c stock_funcs.c
gcc -Wall -Wno-comment -Werror -g -o test_stock_funcs test_stock_funcs.c stock_fun
./testy test_stock1.org
============================================================
== test_stock1.org : Problem 1 First 3 Functions in stock_funcs.c
== Running 15 / 15 tests
1) stock_new : ok
2) stock_free1 : ok
3) stock_free2 : ok
4) stock_free3 : ok
5) stock_free4 : ok
6) stock_print1 : ok
7) stock_print2 : ok
8) stock_print3 : ok
9) stock_print4 : ok
10) stock_print5 : ok
11) stock_print_prices_0 : ok
12) stock_print_prices_1 : ok
13) stock_print_prices_2 : ok
14) stock_print_prices_3 : ok
15) stock_print_final : ok
============================================================
RESULTS: 15 / 15 tests passed
>> make test-prob2 # run tests for problem 2
gcc -Wall -Wno-comment -Werror -g -c stock_main.c
gcc -Wall -Wno-comment -Werror -g -o stock_main stock_main.o stock_funcs.o
./testy test_stock2.org
============================================================
== test_stock2.org : Problem 2 Remaining Functions in stock_funcs.c
== Running 15 / 15 tests
1) stock_set_minmax1 : ok
2) stock_set_minmax2 : ok
Each problem describes specifically how tests can be run and how credit will be assigned.
Note that one can run a single test with the following make invocation which sets testnum.
This is useful when debugging to limit the output and time it takes to check program results.
3 Problem 1: Stock Plotting
3.1 Overview and Demo
Problems 1 and 2 create a small plotting application that is focused on stock prices. In stock trading, the idea is to buy a stock when
it is priced low and sell it at a later time point when the price is high which will net the profit of the difference between each. Of
course, this must be done by predicting when prices are at their highest and lowest points and some insight can be garnered from
examining historical data for stock prices. The application you will build allows for easy analysis of a simple data file containing
times/prices for stocks and display of their information in simple text plots. At the end of problems 1 and 2, you will have an
application which produces the following kind of output.
3) stock_set_minmax3 : ok
4) stock_set_best1 : ok
5) stock_set_best2 and 3 : ok
6) stock_set_best4 : ok
7) count_lines : ok
8) stock_load1 : ok
9) stock_load2 and 3 : ok
10) stock_load pathological : ok
11) stock_plot1 : ok
12) stock_plot2 3 4 : ok
13) stock_plot5 6 : ok
14) stock_main1 : ok
15) stock_main2 : ok
============================================================
RESULTS: 15 / 15 tests passed
> make test # run tests for all problems
…
> make test-prob2 testnum=5
>> ./stock_main 10 data/stock-ascending.txt # plot a stock-ascending data
data_file: data/stock-ascending.txt
count: 10
prices: [10.00, 20.00, 30.00, …] # shows the first few stock p
min_index: 0 # calculates time for min/max
max_index: 9
best_buy: 0 # calculates optimal buy/sell
best_sell: 9
profit: 90.00
max_width: 10 # 10 specifed on command line
range: 90.00 # difference between max/min
plot step: 9.00 # amount represented by each
+———-
0: B MIN 10.00 | # visual representation of st
1: 20.00 | # prices over time
2: 30.00 |##
3: 40.00 |###
4: 50.00 |####
5: 60.00 |#####
6: 70.00 |######
7: 80.00 |#######
8: 90.00 |########
9: S MAX 100.00 |##########
>> ./stock_main 20 data/stock-ascending.txt # same file make the bars big
data_file: data/stock-ascending.txt # 20 hashes wide rather than
count: 10
prices: [10.00, 20.00, 30.00, …]
min_index: 0
max_index: 9
best_buy: 0
profit: 90.00
best_sell: 9
max_width: 20 # 20 specified on command lin
range: 90.00 # makes the bars wider
plot step: 4.50
+——————–
0: B MIN 10.00 |
1: 20.00 |##
2: 30.00 |####
3: 40.00 |######
4: 50.00 |########
5: 60.00 |###########
6: 70.00 |#############
7: 80.00 |###############
8: 90.00 |#################
9: S MAX 100.00 |####################
>> ./stock_main 20 data/stock-valley.txt # plot a different file
data_file: data/stock-valley.txt # which has a valley shape
count: 12
prices: [100.00, 90.00, 80.00, …]
min_index: 5
max_index: 11
best_buy: 5
best_sell: 11
profit: 55.00
max_width: 20
range: 55.00
plot step: 2.75
+——————–
0: 100.00 |##################
1: 90.00 |##############
2: 80.00 |##########
3: 70.00 |#######
4: 60.00 |###
5: B MIN 50.00 |
6: 55.00 |#
7: 65.00 |#####
8: 75.00 |#########
9: 85.00 |############
10: 95.00 |################
11: S MAX 105.00 |####################
>> ./stock_main 20 data/stock-jagged.txt # plot a file with greater
data_file: data/stock-jagged.txt # variance in prices
count: 15
prices: [103.00, 250.00, 133.00, …]
min_index: 8
max_index: 11
best_buy: 8
best_sell: 11
profit: 232.00
max_width: 20
range: 232.00
plot step: 11.60
+——————–
0: 103.00 |#####
1: 250.00 |##################
2: 133.00 |########
3: 143.00 |#########
4: 168.00 |###########
5: 91.00 |####
6: 234.00 |################
7: 59.00 |#
3.2 Outline of stock_funcs.c
The file stock_funcs.c will contain most of the support functions for the stock plotting program. An outline of these functions
are presented below. Note that each function has the Problem # to which it belongs.
8: B MIN 38.00 |
9: 45.00 |
10: 254.00 |##################
11: S MAX 270.00 |####################
12: 59.00 |#
13: 72.00 |##
14: 107.00 |#####
>> ./stock_main 25 data/stock-min-after-max.txt # plot a stock with varying
data_file: data/stock-min-after-max.txt # prices
count: 15
prices: [223.00, 292.00, 27.00, …]
min_index: 10 # minimum price appear after
max_index: 4 # the maximum price
best_buy: 2 # finding the optimal buy/sel
best_sell: 4 # point is harder in this cas
profit: 296.00
max_width: 25
range: 309.00
plot step: 12.36
+————————-
0: 223.00 |################
1: 292.00 |######################
2: B 27.00 |#
3: 92.00 |######
4: S MAX 323.00 |#########################
5: 189.00 |##############
6: 207.00 |###############
7: 142.00 |##########
8: 321.00 |########################
9: 89.00 |######
10: MIN 14.00 |
11: 182.00 |#############
12: 164.00 |############
13: 156.00 |###########
14: 169.00 |############
>> ./stock_main 9 data/stock-descending.txt # if the stock is continually
No viable buy/sell point # declining, its best not to
data_file: data/stock-descending.txt
count: 10
prices: [100.00, 90.00, 80.00, …]
min_index: 9
max_index: 0
best_buy: -1 # not worthwhile to buy/sell
best_sell: -1 # this situation
profit: 0.00
max_width: 9
range: 90.00
plot step: 10.00
+———
0: MAX 100.00 |#########
1: 90.00 |########
2: 80.00 |#######
3: 70.00 |######
4: 60.00 |#####
5: 50.00 |####
6: 40.00 |###
7: 30.00 |##
8: 20.00 |#
9: MIN 10.00 |
// stock_funcs.c: support functions for the stock_main program.
stock_t *stock_new();
// PROBLEM 1: Allocate a new stock struct and initialize its fields.
// Integer fields like ‘count’ and ‘min_index’ should be initialied to
// -1. Pointer fields like ‘prices’ should be initialized to
// NULL. The stock should be heap-allocated using malloc() and
// returned. Since this is an allocation function, no use of ‘free()’
// should appear.
void stock_free(stock_t *stock);
// PROBLEM 1: Free a stock. Check the ‘data_file’ and ‘prices’ fields:
// if they are non-NULL, then free them. Then free the pointer to
// ‘stock’ itself.
void stock_print(stock_t *stock);
// PROBLEM 1: Prints data about a stock that is passed in via a
// pointer. Uses the syntax ptr->field to access fields of the struct
// pointed by ‘stock’. Output follows the general convention:
//
// data_file: data/stock-jagged.txt
// count: 15
// prices: [103.00, 250.00, 133.00, …]
// min_index: 8
// max_index: 11
// best_buy: 8
// best_sell: 11
// profit: 232.00
//
// Where each line prints a field of the stock_t struct. In all cases,
// floating point numbers are printed with 2 decimal digits of accuracy.
//
// NULLS FOR FIELDS
// The fields ‘data_file’ and ‘prices’ may be NULL in which case they
// will be printed specially as in
//
// data_file: NULL
// prices: NULL
//
// This requires a manual if/else check for NULL values for these pointers.
//
// PRICES FIELD
// When printing the ‘prices’ field, if the ‘count’ field is 0 to 3,
// print the entire array as in
//
// prices: [] # count == 0
// prices: [70.00] # count == 1
// prices: [50.00, 90.00] # count == 2
// prices: [59.00, 45.00, 103.00] # count == 3
//
// Otherwise, print the first 3 elements with a … at the end as in
//
// prices: [10.00, 20.00, 30.00, …] # count > 3
//
// PROFIT
// There is no ‘profit’ field in the struct. Instead, calculate the
// profit as the difference between the price at the ‘best_sell’ index
// and ‘best_buy’ index. If these indices are -1 indicating the best
// buy/sell time is not known or not viable, print a proit of 0.0
void stock_set_minmax(stock_t *stock);
// PROBLEM 1: Sets the index of ‘min_index’ and ‘max_index’ fields of
// the stock to be the positions in ‘prices’ of the minimum and
// maximum values present in it. Uses a simple loop over the array
// ‘prices’ which is ‘count’ elements long to examine each for
// max/min. If ‘count’ is zero, makes no changes to ‘min_index’ and
// ‘max_index’.
int stock_set_best(stock_t *stock);
// PROBLEM 2: Sets the ‘best_buy’ and ‘best_sell’ fields of ‘stock’.
// This corresponds to the pair which produces the best profit. On
// determining the best buy/sell indices which produce a positive
// profit, sets these fields in ‘stock’ and returns 0. If there is no
// buy/sell point which would result in a positive profit, sets the
// ‘best_buy’ and ‘best_sell’ indices to -1 and returns -1. Always
// calculates the earliest buy/sell pair of indices that would get the
// best profit: if 5,8 and 5,9 and 7,10 all give the same, maximal
// profit, the best buy/sell indices are set to 5,7.
//
// ALGORITHM NOTES
// One intuitive algorithm to compute this is to try every possible
// buy index (outer loop) and every possible sell index after it
// (inner loop) looking for the maximum profit produced in it. This is
// a O(N^2) algorithm with N=count. Using this algorithm is a good
// start. Some MAKEUP CREDIT will be awarded for implementing a more
// efficient, O(N) algorithm here. See the specification for more details.
int count_lines(char *filename);
// PROBLEM 2: Opens file named ‘filename’ and counts how many times
// the ‘\n’ newline character appears in it which corresponds to how
// many lines of text are in it. Makes use of either fscanf() with
// the %c format to read single characters or alternative I/O
// functions like fgetc(). Closes the file before returning a count of
// how many lines are it it. If for any reason the file cannot be
// opened, prints a message like
//
// Could not open file ‘not-there.txt’
//
// and returns -1 to indicate failure.
int stock_load(stock_t *stock, char *filename);
// PROBLEM 2: Loads a stock from file ‘filename’ into ‘stock’ filling
// its ‘prices’ and ‘count’ fields in. Makes use of the count_lines()
// function to determine how many lines are in the file which will
// dictate ‘count’ and the length of ‘prices’. Allocates space in the
// heap for the stock’s ‘prices’ array, opens the ‘filename’ and
// iterates through reading prices into the array. The data format for
// prices files is
//
// time_03 133.00
// time_04 143.00
// time_05 168.00
// time_06 91.00
//
// where each line has a time as as single string and a price which is
// floating point number. The times can be ignored which can be
// accomplished with a fscanf() call with format “%*s” to read a
// string but ignore/discard it.
//
// Assigns the ‘datafile’ field to be a duplicated string of
// ‘filename’ for which ‘strdup()’ is extremely useful. This string
// must be free()’d later likely in ‘stock_free()’
//
// On successfully loading the stock, returns 0.
//
// If ‘filename’ cannot be opened, prints the message
//
// Unable to open stock file ‘some-stock.txt’, bailing out
//
// with ‘filename’ substituted in for the name of the stock and
// returns -1.
void stock_plot(stock_t *stock, int max_width);
// PROBLEM 2: Plots a graphical representation of stock
// information. First calculates and prints plot which is in the
// following format:
//
// max_width: 25
// range: 40.00
// plot step: 1.60
//
// The prints a header line and iterates through each stock data on it
// along with a bar which varies in width with the stock price. A
// sample format is as follows with some annotations.
//
//….20 spaces…….+ …max_width dashes…..
//01234567890123456789
// +————————-
// 0: 223.00 |################
// 1: 292.00 |######################
// 2: B 27.00 |#
// 3: 92.00 |######
// 4: S MAX 323.00 |#########################
// 5: 189.00 |##############
// 6: 207.00 |###############
// 7: 142.00 |##########
// 8: 321.00 |########################
// 9: 89.00 |######
// 10: MIN 14.00 |
// 11: 182.00 |#############
// 12: 164.00 |############
// 13: 156.00 |###########
// 14: 169.00 |############
//01234567890123456789
//| | | | |
//| | | | +-> Each bar is (price-min)/plot_step hashes wide
//| | | +-> Stock price printed with format %8.2f
//| | +-> Print MIN or MAX if the stock is at min_index/max_index
//| +-> Print B or S if the stock is at the best_buy/best_sell index
//+–> Index in the array printed with format %3d
3.3 Editing and Testing
The project code contains a skeleton version of stock_funcs.c which you should fill in with definitions. With this skeleton
version, you can immediately start testing your code by typing make test-prob1. Without changes, you will get failures for
all tests as in
However, the ability to run tests on your code an see progress is extremely important. Your first goal when starting a new project
should be to see some results or running the program which is much easier if some benevolent dictator has provided a bunch of
tests.
You can also use the invocation
> make test-prob1 testnum=5
to run a single test and see its results in the terminal.
Failed tests generate results files which can be viewed in any text editor or in the terminal. The cat command can show such
results in the terminal via cat test-results/some-file.txt.
>> make test-prob1
gcc -Wall -Wno-comment -Werror -g -o test_stock_funcs test_stock_funcs.c stock_fun
./testy test_stock1.org
============================================================
== test_stock1.org : Problem 1 First 3 Functions in stock_funcs.c
== Running 15 / 15 tests
1) stock_new : FAIL -> results in file ‘test-results/prob1-01-result.tm
2) stock_free1 : FAIL -> results in file ‘test-results/prob1-02-result.tm
3) stock_free2 : FAIL -> results in file ‘test-results/prob1-03-result.tm
…
============================================================
RESULTS: 0 / 15 tests passed
Below the results for the first test are shown and from the comparison and Valgrind report, it appears that there is some sort of
Memory problem with the stock_new() function.
>> cat test-results/prob1-01-result.tmp
* (TEST 1) stock_new
COMMENTS:
** program: ./test_stock_funcs stock_new
** — Failure messages —
– FAILURE(139) due to SIGSEGV (segmentation fault) from OS
– FAILURE: Output Mismatch at lines marked
** — Side by Side Differences —
– Expect output in: test-results/raw/prob1-01-expect.tmp
– Actual output in: test-results/raw/prob1-01-actual.tmp
– Differing lines have a character like ‘|’ ‘>’ or ‘<' in the middle
#+BEGIN_SRC sbs-diff
==== EXPECT ==== ==== ACTUAL =
{ {
// Tests stock_new() function and whether it initializes fields // Tests
// correctly before returning a stock. // correc
stock_t *stock = stock_new(); // call function to allocate/init stock_t *
printf("stock->data_file: %p\n” , stock->data_file); printf(“s
printf(“stock->count: %d\n” , stock->count); printf(“s
printf(“stock->prices: %p\n” , stock->prices); printf(“s
printf(“stock->min_index: %d\n” , stock->min_index); printf(“s
printf(“stock->max_index: %d\n” , stock->max_index); printf(“s
printf(“stock->best_buy: %d\n” , stock->best_buy); printf(“s
printf(“stock->best_sell: %d\n” , stock->best_sell); printf(“s
free(stock); // de-allocate manually free(stoc
} }
stock->data_file: (nil) | Segmentation
stock->count: -1 <
stock->prices: (nil) <
stock->min_index: -1 <
stock->max_index: -1 <
stock->best_buy: -1 <
stock->best_sell: -1 <
#+END_SRC
** --- Line Differences ---
EXPECT: 17) stock->data_file: (nil)
EXPECT: 18) stock->count: -1
EXPECT: 19) stock->prices: (nil)
EXPECT: 20) stock->min_index: -1
EXPECT: 21) stock->max_index: -1
EXPECT: 22) stock->best_buy: -1
EXPECT: 23) stock->best_sell: -1
ACTUAL: 17) Segmentation Fault
— Valgrind Log from: test-results/raw/prob1-01-valgrd.tmp —
==150464== Memcheck, a memory error detector
==150464== Copyright (C) 2002-2017, and GNU GPL’d, by Julian Seward et al.
==150464== Using Valgrind-3.17.0 and LibVEX; rerun with -h for copyright info
==150464== Command: ./test_stock_funcs stock_new
==150464== Parent PID: 150463
==150464==
==150464== Invalid read of size 8
==150464== at 0x109354: main (test_stock_funcs.c:33)
==150464== Address 0x0 is not stack’d, malloc’d or (recently) free’d
==150464==
==150464==
==150464== Process terminating with default action of signal 11 (SIGSEGV): dumping
==150464== Access not within mapped region at address 0x0
3.4 Implementation Notes
Use the Arrow
The first 3 functions to implement in stock_funcs.c are utility functions for stocks to allocate, de-allocate and print them. As
will be covered in lecture, C often deals with pointers to a struct and that is the case in these functions. For this, the sp->fld
syntax is used to first dereference the struct pointer and access a field of the struct. For example, in stock_print() one
could use the following code to print the count field of the parameter struct:
Throughout most of this problem and the next, the Arrow syntax will be used in most functions.
Allocating Stocks in Heap Memory
In order to get dynamically allocated memory in the Heap, the malloc() function should be used. This function takes a number
of bytes and returns a void * pointer for that number of bytes if available. As will be discussed in lecture, C provides the
sizeof() operator to calculate the size of various intrinsic and user-defined types. To allocate enough space for a stock_t, use
malloc(sizeof(stock_t)).
Though malloc() returns a void *, it is typical to simply assign it to a pointer of some other kind. For example, the following
is a typical way to allocate space for a single stock_t struct and save the reference for later use.
Once allocated, the Arrow syntax mentioned above, stock->min_index can be used to adjust fields.
To understand which fields are present in the stock_t struct, open up the header file stock.h which declares the struct. There
will be a list of fields like prices and max_index: these will all need to receive initial values like -1 or NULL. Don’t alter
anything in the header as this may break tests that you’ll run later.
Avoid Freeing NULL
While the free() function is used to de-allocate memory that has been obtained via malloc(), it should never be called with a
NULL pointer. In the stock_free() function, one should check the data_file and prices fields and free them only if they
are not NULL. The following code demonstrates how this can be done for one of those fields.
==150464== at 0x109354: main (test_stock_funcs.c:33)
==150464== If you believe this happened as a result of a stack
==150464== overflow in your program’s main thread (unlikely but
==150464== possible), you can try to increase the size of the
==150464== main thread stack using the –main-stacksize= flag.
==150464== The main thread stack size used in this run was 10022912.
==150464==
==150464== HEAP SUMMARY:
==150464== in use at exit: 0 bytes in 0 blocks
==150464== total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==150464==
==150464== All heap blocks were freed — no leaks are possible
==150464==
==150464== For lists of detected and suppressed errors, rerun with: -s
==150464== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
void print_stock(stock_t *stock){
// …
printf(“count: %d\n”, stock->count);
// ^^^^^^^^^^^^
stock_t *stock = malloc(sizeof(stock_t));
void stock_free(stock_t *stock){
// …
if(stock->data_file != NULL){
free(stock->data_file);
}
// …
Printing Prices Array
During stock_print(), some special code will be needed to print the prices[] array if it has 3 or fewer elements. As per the
function documentation, the line associated with prices will like one of the following depending on the value for count:
There are a couple tricks for producing this type of output and it may take some care to get the output formatted correctly for all
situations. You might try either of the following:
1. Brute force: establish 5 cases for each of the formats above with separate printf() call for each. Since the number of
cases is relatively small, this should not be unmanageable.
2. Use the count==0 as a special case and then write a carefully crafted loop with conditionals to handle the remaining
cases. This can get tricky but is more flexible if for later one wants to see the first 5 numbers instead.
Either approach is acceptable in this case.
Keep in mind that though prices is declared as a double *prices (pointer to double data), it is fine to use array syntax
like square brace indexing with it. Syntax like stock->prices[2] will follow a pointer to a stock_t struct then find the
prices field and index into it as an array.
3.5 Grading Criteria for Problem 1 grading 30
The following criteria will be checked.
Weight Criteria
AUTOMATED TESTS via make test-prob1
15 Runs tests in test_prob1.org on the first 3 functions in stock_funcs.c
Runs all code under Valgrind to ensure that no memory errors are present.
1 point per test passed
MANUAL INSPECTION
5 Overall Style and Readability
Good indentation of code clearly denoting function/loop/conditional scopes
Presence of some comments to indicate intent in gnarly code
5 stock_new() and stock_free()
Appropriate use of malloc() and sizeof() to get heap memory
Correct initialization of all fields to -1 or NULL
Appropriate use of the Arrow syntax for field access
Checks for data_file and prices fields to avoid calling free() on a NULL pointer
Appropriate use of the Arrow syntax for field access
5 stock_print()
Appropriate use of the Arrow syntax for field access
Clear logic which deals with printing prices[] array with 3 or fewer elements specially
prices: [] # count == 0
prices: [70.00] # count == 1
prices: [50.00, 90.00] # count == 2
prices: [59.00, 45.00, 103.00] # count == 3
prices: [10.00, 20.00, 30.00, …] # count > 3
Weight Criteria
Clear section to calculate Profit from best_buy/best_sell or print 0.0 if these are -1
4 Problem 2: Completing Stock Plot
4.1 Overview
This problem implements further functions to complete the Stock Plotting application. These functions are somewhat more
complex and utilize functions and techniques that are part of Problem 1. When this problem is complete, all functions in
stock_funcs.c will be working which will allow the provided stock_main.c program to be compiled and run on the
command line.
The remainder of this section gives some notes and implementation hints on how to handle the various functions.
4.2 Setting Min/Max Index
This function should be implemented as a simple “scan” across the prices[] array. Each step will check an element of
prices[] and adjust a running min/max. Make use of similar syntax here as you used in stock_print() in order to access
the elements of prices and subsequently set the min_index and max_index fields.
4.3 Best Buy/Sell Index
In many cases it is best to buy at a minimum price and sell at a maximum price. This approach fails if the maximum price occurs
before the minimum price. The job of stock_set_best() is to run an algorithm to locate the best possible buy/sell pair and set
the best_buy / best_sell fields of a stock. As the documentation for the function indicates, one can use a simple “brute
force” approach to this by simply trying every buy index paired with every sell index (which must occur later in the array than the
buy index). This approach leads to the following pattern of iteration through the prices array which uses a doubly nested pair of
loops.
Start by adapting this approach in the function and make sure it works. Then move on to solve other problems here.
For those that want a bit more fun, revisit this function later to implement a more efficient version of it as described in the Optional
MAKEUP CREDIT Section.
4.4 Stock Files
Data on stock prices over time are stored in several example files in the data/ directory such as data/stock-
ascending.txt and data/stock-jagged.txt.
void stock_set_minmax(stock_t *stock)
int stock_set_best(stock_t *stock);
set best_buy and best_sell to -1
set best_profit to 0.0
for every buy index I in prices
for every sell index J later than I in prices
if prices[J] – prices[I] > best_profit
set best_buy,best_sell, to I,J
set best_profit to prices[J] – prices[I]
done
done
>> ls data/stock-* # list all the sample stock data
data/stock-1only.txt data/stock-empty.txt data/stock-TSLA-08-02-20
data/stock-2only.txt data/stock-FB-08-02-2021.txt data/stock-TSLA-08-12-20
data/stock-3only.txt data/stock-GOOG-08-02-2021.txt data/stock-valley.txt
data/stock-ascending.txt data/stock-jagged.txt
data/stock-descending.txt data/stock-min-after-max.txt
Each of has a simple data format which looks like the following.
Each time/price pair appears on its own line so that the number of lines in the file is the number of time/price pairs
The first item on each line is a time at which a price appears: this will be ignored.
The second item that appears on each line is a floating point number which is the stock price at that time.
4.5 Counting Lines
Since the number of lines in stock files corresponded to the number of prices, it is useful to have a utility function to count lines in a
file which is required.
As the documentation for the function indicates, this function will open the named file and count the lines in it. This can be done
most easily via treating the file as a long array of characters and looking for the special \n newline character which designates a
line break. Character comparisons are done in C like other equality comparisons via syntax like
To read a single character from a file, a common approach is to use the fscanf() function with the %c format specifier as in
Keep in mind that the fscanf() function will fail to read a character when it reaches the end of a file. In these cases it will return
the special return value EOF which should be checked. A common structure is
Experiment with these elements to complete the count_lines() function.
>> cat data/stock-jagged.txt
time_01 103.00
time_02 250.00
time_03 133.00
time_04 143.00
time_05 168.00
time_06 91.00
time_07 234.00
time_08 59.00
time_09 38.00
time_10 45.00
time_11 254.00
time_12 270.00
time_13 59.00
time_14 72.00
time_15 107.00
int count_lines(char *filename)
if(somevar == ‘\n’){ … }
if(somevar == ‘X’){ … }
char c;
int ret = fscanf(fin, “%c”, &c);
int ret = fscanf(fin, …, …);
if(ret == EOF){
// take action for end of file, like breaking out of a loop
// or returning
}
else{
// fscanf() completed normally so variables should contain
// new values
}
Keep in mind that count_lines() should fail gracefully if a file cannot be opened. In such cases, the fopen() function
returns NULL. Make sure to check for this, print an error message as indicated in the function documentation, and return -1 from
the function to indicate a failure has occurred.
4.6 Loading Stock Files
This function takes an existing stock and fills in its price and count fields based on the contents of the given file. An
example:
Make use of the count_lines() function to determine how many lines are in the stock file. This will allow you to immediately
allocate enough space for a double array for all of the prices in the file.
You will need to skip the first string on each line in prices files:
An easy way to accomplish this is to use the C format modifier * which reads a field but does not place it in memory anywhere. For
example:
would read a string but ignore it thus one does not have to provide a memory address to store the string.
One requirement of stock_load() is to set the data_file field to be a copy of the filename parameter. While this can be
done manually with malloc() and a loop, the strdup() function makes this easy and is encouraged here. Look up
documentation for it either in the Unix man pages (type man strdup in a terminal) or via an internet search.
Ensure that at the end of stock_load() the data_file, prices, and count fields have been set according to the data from
the file. Do not modify any other fields in the stock.
4.7 Plotting Stocks
The ultimate goal of the Stock Plot application is fulfilled in this function which is meant to print a graphical representation of
stock data. A sample of output is below and will be discussed in more detail.
int stock_load(stock_t *stock, char *filename)
stock_t *stock = new_stock();
// all fields of stock have default values like -1 and NULL
int ret = stock_load(stock, “data/stock-ascending.txt”);
// Specified data file as 10 lines so
// stock->count is now 10
// stock->prices is an array of 10 values read from the file
// If the load failed, -1 would be returned
time_03 133.00
time_04 143.00
| |
| +—> Read these into prices
+—> Skip these times
fscanf(fin, “%*s”);
void stock_plot(stock_t *stock, int max_width);
max_width: 25
range: 40.00
plot step: 1.60
+————————-
0: 223.00 |################
1: 292.00 |######################
The output comes from the following code fragment which is present in the provided file stock_demo.c.
The initial output is
and shows the calculation needed to compute the “plot step”. This relies on knowing the Minimum and Maximum price (found via
stock_set_minmax()) to first get the Range (difference between min/max). The range is then divided by the max_width
parameter. max_width dictates how wide the widest “bar” of the plot should be. The reported “plot step” is 1.60 in this case so
that each of the # has marks corresponds to 1.60 in price in the below bars.
Next an axis line appears as in
The left area has a fixed number of spaces followed by a + then a number of dashes equal to the max_width parameter. Use a
loop to print out the proper number of dashes.
The remainder of the plot has one line per stock price. Examples of the first few lines:
Note that the initial index at the left is printed with format %3d which leaves spaces on the left for single and double digit numbers.
Next appears the price for the stock at that time. This is printed using the format specifier %8.2f which leaves 2 digits beyond the
decimal place and again, may add some space on the left for smaller prices.
At the right, each “bar” has a length which can be computed by the formula
int width = (price[i] – minimum_price) / plot_step
This will convert a double value into an integer which can then be used in a loop to print out the proper number of # marks.
2: B 27.00 |#
3: 92.00 |######
4: S MAX 323.00 |#########################
5: 189.00 |##############
6: 207.00 |###############
7: 142.00 |##########
8: 321.00 |########################
9: 89.00 |######
10: MIN 14.00 |
11: 182.00 |#############
12: 164.00 |############
13: 156.00 |###########
14: 169.00 |############
{
stock_t *stock = stock_new();
stock_load(stock, “data/stock-min-after-max.txt”);
stock_set_minmax(stock);
stock_set_best(stock);
stock_plot(stock, 25);
}
max_width: 25
range: 40.00
plot step: 1.60
+————————-
….20 spaces…. ….max_width dashes…..
// 0: 223.00 |################
// 1: 292.00 |######################
The space in between the index and the price is used to denote the optimal buy/sell time and the min/max stock prices. As a couple
examples here are possible outputs that combine some of these.
Use a B or S at the index that matches best_buy / best_sell. Print this as a single character string OR print a space
here if the stock is not at the best buy/sell index.
Print MAX or MIN if the stock is at the min/max index or print 3 spaces if not. In either case follow with 1 more space.
A common tactic to solve such problems is to use a conditional structure like the following which re-assigns a string based on
whether a particular stock price is one of the best buy/sell or min/max.
The same process can be executed to print out either a blank space or B/S for the best buy/sell designator as well.
It may take some time to get the output for the stock_plot() correct but this can be expedited through careful inspection of test
feedback.
4.8 Optional MAKEUP CREDIT
The “brute force” approach initially suggested to find best_buy / best_sell indices compares all possible buy/sell pairs to
determine the best profit possible. This is a Quadratic algorithm with complexity O(N^2) with N being the length of the
prices[] array.
One can improve upon this algorithm to get an O(N) linear algorithm. This takes some cleverness or some research. For example,
the problem is directly related to the Maximum Subarray Problem and its various solutions. These are described here:
https://en.wikipedia.org/wiki/Maximum_subarray_problem
https://medium.com/@rsinghal757/kadanes-algorithm-dynamic-programming-how-and-why-does-it-work-3fd8849ed73d
https://cs.gmu.edu/~kauffman/cs310/01-intro.pdf
Note that adapting these approaches to the current setting will require some care: the Maximum Subarray problem assumes
elements in the array are added together whereas in our Stock setting, it is the difference between elements that matter. However,
buy absorbing the tricks used the linear time Maximum Subarray algorithm, one can get the same effect for the Stocks, an O(N)
algorithm to set best_buy / best_sell.
Code that implements a Linear Time algorithm for stock_set_best() will be awarded 10 POINTS of PROJECT
MAKEUP CREDIT.
Makeup Credit will go into the general pool of points earned for projects to make up for points missed on projects elsewhere. If a
student scores 110/100 on Project 1 and 90 / 100 on Project 2, the 10 points from Project 1 will make up for the credit lost on
Project 2. Your total score on All Projects cannot exceed 100% so any points beyond the overall total will simply be dropped.
4.9 Grading Criteria for Problem 2 grading 30
The following criteria will be checked.
Weight Criteria
AUTOMATED TESTS via make test-prob2
15 Runs the tests provided in test_prob2.org for last functions in stock_funcs.c and stock_main
Runs all code under Valgrind to ensure that no memory errors are present.
2: B 27.00 |#
4: S MAX 323.00 |#########################
10: MIN 14.00 |
char *min_or_max_str = ” “;
if(i == stock->min_index){
min_or_max_str = “MIN”;
}
if(i == stock->max_index){
…
}
printf(“%s “,min_or_max_string);
https://en.wikipedia.org/wiki/Maximum_subarray_problem
https://medium.com/@rsinghal757/kadanes-algorithm-dynamic-programming-how-and-why-does-it-work-3fd8849ed73d
https://cs.gmu.edu/~kauffman/cs310/01-intro.pdf
Weight Criteria
1 point per test passed
MANUAL INSPECTION
5 stock_set_minmax() and stock_set_best()
Clear loop to scan through the prices array to find the min/max and best buy/sell
Proper changes to the fields min_index / max_index / best_buy / best_sell
5 stock_load() and count_lines()
Use of fopen() and fscanf() to read in data from the file
Code to gracefully handle failure to open a file and print appropriate messages.
Proper use of count_lines() to determine the number of lines in the data file
Use of malloc() to allocate memory for the prices array
Use of the “%*s” format specifier to skip leading “time” string in files
Duplication of the filename to the data_file field likely using the strdup() function
5 stock_plot()
Clear section that calculates the “plot step” with appropriate variables like range
Code to print out the initial plot information and loop to print the upper axis “bar”
Section of conditional code which prints if stock is min/max and best buy/sell
Clear loop that prints out bars with width proportional to the price of the stock
10 OPTIONAL MAKEUP CREDIT
Implement stock_set_best() in linear time rather than Quadratic time.
Such solutions will have a single loop rather than 2 nested loops BUT not every single loop
is linear time. Credit will be deducted if the code is not concise and clear.
5 Problem 3: Tree Sets in C
5.1 Overview
This problem implements a rudimentary “tree set” application in C along with a program that uses it. The architecture is similar to a
HW problem involving linked lists so reviewing that code can provide some insight.
Basic Binary Search Trees are covered in most introductory data structure classes such as CSCI 1913 and 1933. A “Tree Set” is
simply a binary search tree which only allows one copy of each unique item in it. When searching for an item, the organization of
the binary search tree is exploited to speed up the location of the time or determine that it is not present. When adding items,
duplicate items are discarded without altering the tree.
5.2 treeset_main Demonstration
The intent of this problem is to develop a small application which behaves as the following demo indicates. Study this demo
carefully as it illustrates most of the capabilities of the application with each capability being checked by automated tests.
> make treeset_main # build with Makefile
gcc -Wall -Wno-comment -Werror -g -c treeset_main.c
gcc -Wall -Wno-comment -Werror -g -c treeset_funcs.c
gcc -Wall -Wno-comment -Werror -g -o treeset_main treeset_main.o treeset_funcs.o
> ./treeset_main # run main program
Treeset Main
Commands:
print: shows contents of the tree in reverse sorted order
size: prints the number of nodes currently in the tree
clear: eliminates all elements from the tree
quit: exit the program
add
find
preorder: prints contents of the tree in pre-order which is how it will be
save
load
TS#> add Lucas # add some data
TS#> add Mike
TS#> add Dustin
TS#> add Will
TS#> add El
TS#> size # show number of nodes in the tree
5 nodes
TS#> print # print tree, reverse order, indentation indicates
Will # root->right->right
Mike # root->right
Lucas # root
El # root->left->right
Dustin # root->left
TS#> preorder # show tree in preorder, root first
Lucas # root
Dustin # root->left
El # root
Mike # root->right
Will # root->right->right
TS#> find Mike
FOUND
TS#> find Nancy
NOT FOUND
TS#> add Nancy # add Nancy
TS#> size # show size of tree has increased
6 nodes
TS#> print
Will
Nancy # root->right->right->left
Mike
Lucas
El
Dustin
TS#> add Mike # adding duplicates is ignored
duplicate element ignored
TS#> add El
duplicate element ignored
TS#> find Max
NOT FOUND
TS#> add Max # add max
TS#> print
Will
Nancy
Mike # root->right->left
Max
Lucas
El
Dustin
TS#> find Max
FOUND
TS#> find Barb
NOT FOUND
TS#> add Barb # add Barb
TS#> print
Will
Nancy
5.3 tree_funcs.c: tree functions
Examine the header file tree.h to see the two C structs which will be used to represent trees.
Mike
Max
Lucas
El
Dustin
Barb # root->left->left
TS#> save stranger.tree # save tree into named file
TS#> clear # eliminate tree
TS#> size # show tree is empty now
0 nodes
TS#> print # print shows nothing: empty tree
TS#> add Demigorgon # add Demigorgon to empty
TS#> print
Demigorgon # root
TS#> load stranger.tree # clear tree, replace with contents of file
TS#> size # 8 nodes loaded from file
8 nodes
TS#> print # tree is restored
Will
Nancy
Mike
Max
Lucas
El
Dustin
Barb
TS#> add Jim # add Jim
TS#> add Joyce # add Joyce
TS#> print # show tree
Will
Nancy
Mike
Max
Lucas # root
Joyce # root->left->right->right->right
Jim # root->left->right->right
El
Dustin
Barb
TS#> load stranger.tree # clear and reload from file
TS#> print # restored to previous contents
Will
Nancy
Mike
Max
Lucas
El
Dustin
Barb
TS#> quit # quit program
// Nodes that go into the tree
typedef struct tsnode {
char name[128]; // tsnode data
struct tsnode *left; // left branch, NULL if not present
struct tsnode *right; // right branch, NULL if not present
} tsnode_t;
// Type of tree itself
typedef struct {
tsnode_t *root; // root of tree, NULL if tree empty
The tree set will track unique strings each of which is stored in a tsnode_t struct. The treeset_t struct tracks the root of the
tree along with the total number of nodes in the tree.
Standard operations are supported by the tree.
Inserting item
Searching for an element
Clearing the entire tree
Printing tree in reverse sorted order which is handy for visualization
Printing the tree in pre-order (root first, then children) which is useful for saving and loading to files
Saving and loading from a file
These are broken down into the following C functions which you will need to implement in the file treeset_funcs.c. Keep in
mind that to honor the binary search tree property (left less than / right greater than), you will need to use the return values of
strcmp() function calls as string data is present in the tree.
Below is an outline of the functions that should be present in treeset_funcs.c along with guiding documentation about how
to implement them.
// treeset_funcs.c: Provides a small library of functions that operate
// on binary search trees of unique strings.
void treeset_init(treeset_t *tree);
// Initialize the given tree to have a null root and have size 0.
int treeset_insert(treeset_t *tree, char name[]);
// Inserts given name into a binary search tree. Uses an ITERATIVE
// (loopy) approach to insertion which starts a pointer at the root of
// the tree and changes its location until the correct insertion point
// is located. Returns 1 if a new tsnode is created and 0 if a duplicate
// name is found in the tree already in which case the name is not
// added.
int treeset_find(treeset_t *tree, char name[]);
// Determines whether name is present or not in the tree using binary
// search. Returns 1 if name is present and 0 otherwise. Uses an
// ITERATIVE (loopy) approach which starts a pointer at the root of
// the tree and changes it until the search name is found or
// determined to not be in the tree.
void treeset_clear(treeset_t *tree);
// Eliminate all tsnodes in the tree setting its contents empty. Uses
// recursive tsnode_remove_all() function to free memory for all tsnodes.
void tsnode_remove_all(tsnode_t *cur);
// Recursive helper function which visits all tsnodes in a tree and
// frees the memory associated with them. This requires a post-order
// traversal: visit left tree, visit right tree, then free the cur
// tsnode.
void treeset_print_revorder(treeset_t *tree);
// Prints the elements of the tree in reverse order at differing
// levels of indentation which shows all elements and their structure
// in the tree. Visually the tree can be rotated clockwise to see its
// structure.
void tsnode_print_revorder(tsnode_t *cur, int indent);
// Recursive helper function which prints all elements in the tree
// rooted at cur in reverse order: traverses right subtree, prints cur
// tsnode, traverses left tree. Parameter ‘indent’ indicates how far to
// indent (2 spaces per indent level).
void treeset_print_preorder(treeset_t *tree);
// Print all the data in the tree in pre-order with indentation
// corresponding to the depth of the tree. Makes use of
int size; // number of tsnodes in tree
} treeset_t;
// tsnode_write_preorder() for this.
void treeset_save(treeset_t *tree, char *fname);
// Saves the tree by opening the named file, writing the tree to it in
// pre-order with tsnode_write_preorder(), then closing the file.
void tsnode_write_preorder(tsnode_t *cur, FILE *out, int depth);
// Recursive helper function which writes/prints the tree in pre-order
// to the given open file handle. The parameter depth gives how far to
// indent tsnode data, 2 spaces per unit depth. Depth increases by 1 on
// each recursive call. The function prints the cur tsnode data,
// traverses the left tree, then traverses the right tree.
int treeset_load(treeset_t *tree, char *fname );
// Clears the given tree then loads new elements to it from the
// named. Repeated calls to treeset_insert() are used to add strings read
// from the file. If the tree is stored in pre-order in the file, its
// exact structure will be restored. Returns 1 if the tree is loaded
// successfully and 0 if opening the named file fails in which case no
// changes should be made to the tree.
5.4 treeset_main.c: main function / application
In treeset_main.c implement an interactive program which allows users to type commands to manipulate a treeset. Most of
these commands will dispatch directly to an analogous function in treeset_funcs.c. Example: the add command will likely
call treeset_insert().
Once the files treeset_funcs.c and treeset_main.c are present, the provided Makefile should compile the complete
program and allow it to run as follows:
The following sections provide some implementation details.
Read commands, Execute
The basic flow of tree_main.c follows a provided lab exercise code closely.
Create a tree variable, likely on the stack as a local variable in main()
Start a loop that terminates when the user exits or there is no more input
Each time the user enters a string, read it and check for one of the built-in commands
On identifying the command, potentially read another string if needed (commands like add and find)
Call an appropriate treeset_XXX() function to handle the command
Note that each of the commands that is mentioned such as print and clear will need to do a specific action in the program so
likely a large if/else if/else control structure will feature in most implementations.
Supported Commands
>> make treeset_main
gcc -Wall -Wno-comment -Werror -g -c treeset_main.c
gcc -Wall -Wno-comment -Werror -g -c treeset_funcs.c
gcc -Wall -Wno-comment -Werror -g -o treeset_main treeset_main.o treeset_funcs.o
>> ./treeset_main
Treeset Main
Commands:
print: shows contents of the tree in reverse sorted order
size: prints the number of nodes currently in the tree
clear: eliminates all elements from the tree
quit: exit the program
add
find
preorder: prints contents of the tree in pre-order which is how it will be
save
load
TS#>
To indicate to users of the program the supported commands, use the following code to print out the initial option list.
Paths to Tree files for Saving and Loading
Saving and loading trees involves writing to files. The names associated with the files must be specified as a path so that if tree files
are to be saved or loaded from subdirectories, include this as part of the path. For example, the stranger.tree file is provided
in the data/ directory so can be loaded as follows.
Command Echoing: -echo option to treeset_main
Some users may wish to “script” this the tree program. An example of such a script is in data/stranger-demo.script
which looks like a lot of user commands:
printf(“Treeset Main\n”);
printf(“Commands:\n”);
printf(” print: shows contents of the tree in reverse sorted order\n”);
printf(” size: prints the number of nodes currently in the tree\n”);
printf(” clear: eliminates all elements from the tree\n”);
printf(” quit: exit the program\n”);
printf(” add
printf(” find
printf(” preorder: prints contents of the tree in pre-order which is how i
printf(” save
printf(” load
> ./treeset_main
…
TS#> load data/stranger.tree # load the provided tree from a subdirect
TS#> print # show in reverse sorted order
Will
Nancy
Mike
Max
Lucas
El
Dustin
Barb
TS#> preorder # show in preorder
Lucas
Dustin
Barb
El
Mike
Max
Will
Nancy
TS#> add Demigorgon # add more data
TS#> save cur.tree # save in the current directory
TS#> clear
TS#> print
TS#> load cur.tree # load cur.tree from the current director
TS#> print
Will
Nancy
Mike
Max
Lucas
El
Dustin
Demigorgon # added prior to the save
Barb
TS#> add Jim # add more data
TS#> save data/other.tree # save to a new file in data/ subdir
TS#> quit
This can be fed directly to the program without needing type it using Unix pipes as per the following:
Notice the use of a command line argument for treeset_main: the -echo option. This is a REQUIRED feature which prints
commands typed by users to the screen. To implement this, do the following.
Model the structure of command echoing after what is shown in related Lab work.
Use a variable in main() to indicate whether command echoing is on or off; set it to off by default
Check when main() starts whether command line argument 1 is set to -echo in which case turn echoing on. A condition
like the following is useful.
Each command should check for echoing and print the command being run along with any arguments to it. This technique
is demonstrated in related lab work.
It will take some work to get the exact placement of echoes correct but will ultimately lead to nice results that involve LITTLE
typing like the example below.
add Lucas
add Mike
add Dustin
add Will
add El
size
print
preorder
find Mike
find Nancy
add Nancy
size
print
add Mike
add El
find Max
add Max
print
find Max
find Barb
add Barb
print
save stranger.tree
clear
size
print
add Demigorgon
print
load stranger.tree
size
print
add Jim
add Joyce
print
load stranger.tree
print
quit
> cat data/tree-demo.script | ./treeset_main -echo
if(argc > 1 && strcmp(“-echo”,argv[1])==0) {
>> cat data/stranger-demo.script | ./treeset_main -echo
Treeset Main
Commands:
print: shows contents of the tree in reverse sorted order
size: prints the number of nodes currently in the tree
clear: eliminates all elements from the tree
quit: exit the program
add
find
preorder: prints contents of the tree in pre-order which is how it will be
save
load
TS#> add Lucas
TS#> add Mike
TS#> add Dustin
TS#> add Will
TS#> add El
TS#> size
5 nodes
TS#> print
Will
Mike
Lucas
El
Dustin
TS#> preorder
Lucas
Dustin
El
Mike
Will
TS#> find Mike
FOUND
TS#> find Nancy
NOT FOUND
TS#> add Nancy
TS#> size
6 nodes
TS#> print
Will
Nancy
Mike
Lucas
El
Dustin
TS#> add Mike
duplicate element ignored
TS#> add El
duplicate element ignored
TS#> find Max
NOT FOUND
TS#> add Max
TS#> print
Will
Nancy
Mike
Max
Lucas
El
Dustin
TS#> find Max
FOUND
TS#> find Barb
NOT FOUND
TS#> add Barb
TS#> print
Will
Nancy
Mike
Max
Lucas
El
5.5 Grading Criteria for Problem 3 grading 40
The following criteria will be checked in this problem.
Weight Criteria
AUTOMATED TESTS via make test-prob3
20 test_treeset.org tests
20 tests for treeset_main executable, exercises functions in treeset_funcs.c
All tests run under Valgrind
1 point per test passed
Code compiles without warnings (make clean followed by make test-prob3 gives no errors/warnings)
NOTE: run individual tests via make test-prob3 testnum=4
MANUAL INSPECTION
Dustin
Barb
TS#> save stranger.tree
TS#> clear
TS#> size
0 nodes
TS#> print
TS#> add Demigorgon
TS#> print
Demigorgon
TS#> load stranger.tree
TS#> size
8 nodes
TS#> print
Will
Nancy
Mike
Max
Lucas
El
Dustin
Barb
TS#> add Jim
TS#> add Joyce
TS#> print
Will
Nancy
Mike
Max
Lucas
Joyce
Jim
El
Dustin
Barb
TS#> load stranger.tree
TS#> print
Will
Nancy
Mike
Max
Lucas
El
Dustin
Barb
TS#> quit
>>
Weight Criteria
15 treeset_funcs.c
Clear commenting indicating intent during functions such as “go left” or “item found”
Clear use of binary search principle: left for less, right for greater, use of string functions for this
Effective use of iteration in insert and find functions
Effective use of recursion in printing and removal functions
Relatively short functions: nothing needs to be too long (40 lines tops)
Correct order of visiting/freeing in tsnode_remove_all()
Use of one general tsnode_write_preorder in both treeset_print_preorder() and
treeset_save()
Tree cleared prior to load in treeset_load() to prevent memory leaks
File closed after finished during saving and loading
5 treeset_main.c
Comments indicating what high-level command is being implemented in each part of main
Clear structure of main loop, reading commands, selecting actions
Use of string functions to identify which command to execute
Easy to recognize reading of additional arguments for add/find/etc.
Clear efforts to honor -echo option and echo commands
Clear effort to free all memory prior to exit by clearing tree on exit
6 Project Submission
6.1 Submit to Gradescope
Some of the pictures below mention ‘Assignment’ which is now ‘Project’ and may mention some files that are not part of the current
project. The process of uploading submission is otherwise the same.
1. In a terminal, change to your project code directory and type make zip which will create a zip file of your code. A session
should look like this:
> cd Desktop/2021/p1-code # location of assignment code
> ls
Makefile stock_main.c stock_funcs.c treeset_main.c
…
> make zip # create a zip file using Makefile target
rm -f p1-code.zip
cd .. && zip “p1-code/p1-code.zip” -r “p1-code”
adding: p1-code/ (stored 0%)
adding: p1-code/Makefile (deflated 68%)
adding: p1-code/test_prob1.org (deflated 69%)
adding: p1-code/treeset_main.c (deflated 71%)
…
Zip created in p1-code.zip
> ls p1-code.zip
p1-code.zip
2. Log into Gradescope and locate and click ‘Project 1’ which will open up submission
3. Click on the ‘Drag and Drop’ text which will open a file selection dialog; locate and choose your p1-code.zip file
https://www.gradescope.com/
4. This will show the contents of the Zip file and should include your C source files along with testing files and directories.
5. Click ‘Upload’ which will show progress uploading files. It may take a few seconds before this dialog closes to indicate that
the upload is successful. Note: there is a limit of 256 files per upload; normal submissions are not likely to have problems
with this but you may want to make sure that nothing has gone wrong such as infinite loops creating many files or
incredibly large files.
WARNING: There is a limit of 256 files per zip. Doing make zip will warn if this limit is exceeded but uploading to
Gradescope will fail without any helpful messages if you upload more the 256 files in a zip.
6. Once files have successfully uploaded, the Autograder will begin running the command line tests and recording results.
These are the same tests that are run via make test.
7. When the tests have completed, results will be displayed summarizing scores along with output for each batch of tests.
6.2 Late Policies
You may wish to review the policy on late project submission which will cost 1 Engagement Point per day late. No projects will be
accepted more than 48 hours after the deadline.
https://www-users.cs.umn.edu/~kauffman/2021/syllabus.html
Author: Chris Kauffman ( )
Date: 2021-09-28 Tue 15:18
https://www-users.cs.umn.edu/~kauffman/2021/syllabus.html
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