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: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 thestock_t
type and an incorrect comment mentioning ahashset
. They do not affect any other parts of the project but have been removed to reduce confusion such as what appeared in Post 41.
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
- Download the code associated with the project linked at the top of the spec. Unzip it and examine some of the provided code.
- 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.
- 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.
- Ask questions: if its not clear how to proceed, put up a Piazza post or visit an office hour.
- Get coding: don't wait to start for too long as this will greatly increase your stress level an potentially result in late submissions.
- 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 |
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 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_funcs.o 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
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
.
> 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
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.
>> make test-prob1 # run tests for problem 1, compiles required code first 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_funcs.o ./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 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 ...
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
.
> make test-prob2 testnum=5
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.
>> ./stock_main 10 data/stock-ascending.txt # plot a stock-ascending data file data_file: data/stock-ascending.txt count: 10 prices: [10.00, 20.00, 30.00, ...] # shows the first few stock prices min_index: 0 # calculates time for min/max price max_index: 9 best_buy: 0 # calculates optimal buy/sell time best_sell: 9 profit: 90.00 max_width: 10 # 10 specifed on command line for bar width range: 90.00 # difference between max/min stock plot step: 9.00 # amount represented by each plot hash +---------- 0: B MIN 10.00 | # visual representation of stock 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 bigger: data_file: data/stock-ascending.txt # 20 hashes wide rather than 10 wide 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 line which 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 |# 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/sell best_sell: 4 # point is harder in this case 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 buy 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 in 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 |
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.
// 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
>> make test-prob1 gcc -Wall -Wno-comment -Werror -g -o test_stock_funcs test_stock_funcs.c stock_funcs.o ./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.tmp' 2) stock_free1 : FAIL -> results in file 'test-results/prob1-02-result.tmp' 3) stock_free2 : FAIL -> results in file 'test-results/prob1-03-result.tmp' ... ============================================================ RESULTS: 0 / 15 tests passed
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
.
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 stock_new() function and whether it initializes fields // correctly before returning a stock. // correctly before returning a stock. stock_t *stock = stock_new(); // call function to allocate/init stock_t *stock = stock_new(); // call function to allocate/init printf("stock->data_file: %p\n" , stock->data_file); printf("stock->data_file: %p\n" , stock->data_file); printf("stock->count: %d\n" , stock->count); printf("stock->count: %d\n" , stock->count); printf("stock->prices: %p\n" , stock->prices); printf("stock->prices: %p\n" , stock->prices); printf("stock->min_index: %d\n" , stock->min_index); printf("stock->min_index: %d\n" , stock->min_index); printf("stock->max_index: %d\n" , stock->max_index); printf("stock->max_index: %d\n" , stock->max_index); printf("stock->best_buy: %d\n" , stock->best_buy); printf("stock->best_buy: %d\n" , stock->best_buy); printf("stock->best_sell: %d\n" , stock->best_sell); printf("stock->best_sell: %d\n" , stock->best_sell); free(stock); // de-allocate manually free(stock); // de-allocate manually } } stock->data_file: (nil) | Segmentation Fault 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 core ==150464== Access not within mapped region at address 0x0 ==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)
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
:
void print_stock(stock_t *stock){ // ... printf("count: %d\n", stock->count); // ^^^^^^^^^^^^
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.
stock_t *stock = malloc(sizeof(stock_t));
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.
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
:
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
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:
- 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. - 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 |
|
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
void stock_set_minmax(stock_t *stock)
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
int stock_set_best(stock_t *stock);
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.
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
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
.
>> ls data/stock-* # list all the sample stock data data/stock-1only.txt data/stock-empty.txt data/stock-TSLA-08-02-2021.txt data/stock-2only.txt data/stock-FB-08-02-2021.txt data/stock-TSLA-08-12-2021.txt 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.
>> 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
- 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.
int count_lines(char *filename)
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
if(somevar == '\n'){ ... } if(somevar == 'X'){ ... }
To read a single character from a file, a common approach is to use
the fscanf()
function with the %c
format specifier as in
char c; int ret = fscanf(fin, "%c", &c);
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
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 }
Experiment with these elements to complete the count_lines()
function.
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
int stock_load(stock_t *stock, char *filename)
This function takes an existing stock
and fills in its price
and
count
fields based on the contents of the given file. An example:
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
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:
time_03 133.00 time_04 143.00 | | | +---> Read these into prices +---> Skip these times
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:
fscanf(fin, "%*s");
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
void stock_plot(stock_t *stock, int max_width);
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.
max_width: 25 range: 40.00 plot step: 1.60 +------------------------- 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 |############
The output comes from the following code fragment which is present in
the provided file stock_demo.c
.
{ 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); }
The initial output is
max_width: 25 range: 40.00 plot step: 1.60
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
+------------------------- ....20 spaces.... ....max_width dashes.....
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:
// 0: 223.00 |################ // 1: 292.00 |######################
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.
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.
2: B 27.00 |# 4: S MAX 323.00 |######################### 10: MIN 14.00 |
- Use a
B
orS
at the index that matchesbest_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
orMIN
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.
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);
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. | |
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 <name>: inserts the given string into the tree, duplicates ignored find <name>: prints FOUND if the name is in the tree, NOT FOUND otherwise preorder: prints contents of the tree in pre-order which is how it will be saved save <file>: writes the contents of the tree in pre-order to the given file load <file>: clears the current tree and loads the one in the given file 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 depth/structure 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 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
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.
// 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 int size; // number of tsnodes in tree } treeset_t;
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 // 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:
>> 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 <name>: inserts the given string into the tree, duplicates ignored find <name>: prints FOUND if the name is in the tree, NOT FOUND otherwise preorder: prints contents of the tree in pre-order which is how it will be saved save <file>: writes the contents of the tree in pre-order to the given file load <file>: clears the current tree and loads the one in the given file TS#>
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
andfind
) - 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
To indicate to users of the program the supported commands, use the following code to print out the initial option list.
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 <name>: inserts the given string into the tree, duplicates ignored\n"); printf(" find <name>: prints FOUND if the name is in the tree, NOT FOUND otherwise\n"); printf(" preorder: prints contents of the tree in pre-order which is how it will be saved\n"); printf(" save <file>: writes the contents of the tree in pre-order to the given file\n"); printf(" load <file>: clears the current tree and loads the one in the given file\n");
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.
> ./treeset_main ... TS#> load data/stranger.tree # load the provided tree from a subdirectory 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 directory 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
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:
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
This can be fed directly to the program without needing type it using Unix pipes as per the following:
> cat data/tree-demo.script | ./treeset_main -echo
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.if(argc > 1 && strcmp("-echo",argv[1])==0) {
- 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.
>> 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 <name>: inserts the given string into the tree, duplicates ignored find <name>: prints FOUND if the name is in the tree, NOT FOUND otherwise preorder: prints contents of the tree in pre-order which is how it will be saved save <file>: writes the contents of the tree in pre-order to the given file load <file>: clears the current tree and loads the one in the given file 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 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 >>
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 | |
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.
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
Log into Gradescope and locate and click 'Project 1' which will open up submission
Click on the 'Drag and Drop' text which will open a file selection dialog; locate and choose your
p1-code.zip
fileThis will show the contents of the Zip file and should include your C source files along with testing files and directories.
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.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
.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.