COMP1511 22T1 Programming Fundamentals | Processing of characters and strings | Use of functions and

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5/12/22, 11:47 AM

COMP1511 22T1 — Week 07 Laboratory Sample Solutions

Programming Fundamentals Objectives processing of characters and strings use of functions an introduction to encryption & decryption

Activities To Be Completed The following is a list of all the activities available to complete this week...

Worth one mark in total: devowel word_square string_to_lower Worth half a mark in total: caesar substitution Worth half a mark in total: decode For your interest, but not for marks: word_search You must complete all one for and two dot exercises to get full marks in the problem set for the Week.

Any three dot exercises you complete will form extra bonus marks to make up for any other missing marks in the problem set component.

For more details, see the course outline.

Preparation Before the lab you should re-read the relevant lecture slides and their accompanying examples.

When attempting the following exercises, make sure to read the whole exercise, including any hints and assumptions that may make the exercise easier.

exercise (●◌◌):

Devowelling Text Write a C program devowel.c which reads characters from its input and writes the same characters to its output, except it does not write lower case vowels ('a', 'e', 'i', 'o', 'u').

Your program should stop only at the end of input.

For example:

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

$ ./devowel Are you saying 'Boo' or 'Boo-Urns'?

Ar y syng 'B' r 'B-Urns'?

In this house, we obey the laws of thermodynamics!

In ths hs, w by th lws f thrmdynmcs!

Ctrl-D

HINT:

When completing this task, we suggest you do the following: Scan in, and (maybe) print a single character at a time (you will not need a string for this question).

Write a seperate function to determine if something is a vowel.

Remember, you can use Ctrl+D to finish giving input.

Also recall that previously, when we used scanf to read characters, we always wanted a space before the %c . This allowed us to skip any whitespace (spaces, newlines, etc.) that the user typed. In this exercise, we want to read this whitespace, so we should not have a space before our %c .

You can run an automated code style checker using the following command: $ 1511 style devowel.c

When you think your program is working, you can use autotest to run some simple automated tests: $ 1511 autotest devowel

When you are finished working on this exercise, you and your lab partner must both submit your work by running give : $ give cs1511 lab07_devowel devowel.c

Note, even though this is a pair exercise, you both must run give from your own account before Monday 04 April 20:00 to obtain the marks for this lab exercise.

Sample solution for devowel.c

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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// // //

COMP1511 22T1 — Week 07 Laboratory Sample Solutions

Written 3/3/2018 by Andrew Taylor (andrewt@unsw.edu.au) read characters from stdin and write to stdout except lower case vowels ('a', 'e','i', 'o', 'u') are not written

#include <stdio.h> int is_vowel(int character); int main(void) { // getchar returns an int which will contain either // the ASCII code of the character read or EOF int character = getchar(); while (character != EOF) { if (!is_vowel(character)) { putchar(character); } character = getchar(); } return 0; } // return 1 if character is a lower case vowel // 0 otherwise int is_vowel(int character) { return character == 'a' || character == 'e' || character == 'i' || character == 'o' || character == 'u'; }

exercise (●◌◌):

Word Square Write a program called word_square.c that prompts the user to enter a word, and afterwards, prints that word out n amount of times, where n is the length of the word.

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

$ ./word_square Input word: a Word square is: a $ ./word_square Input word: word Word square is: word word word word $ ./word_square Input word: abrakadabra Word square is: abrakadabra abrakadabra abrakadabra abrakadabra abrakadabra abrakadabra abrakadabra abrakadabra abrakadabra abrakadabra abrakadabra

You can assume that you will be given a word no longer than 1024 character (Including the null-terminator).

You can run an automated code style checker using the following command: $ 1511 style word_square.c

When you think your program is working, you can use autotest to run some simple automated tests: $ 1511 autotest word_square

When you are finished working on this exercise, you and your lab partner must both submit your work by running give : $ give cs1511 lab07_word_square word_square.c

Note, even though this is a pair exercise, you both must run give from your own account before Monday 04 April 20:00 to obtain the marks for this lab exercise.

Sample solution for word_square.c // Program to take in a word and print it out by its length amount of times. // Written by Rory Golledge (z5308772) on October 2021 #include <stdio.h> #include <string.h> #define MAX_WORD 1024 int main(void) { char word[MAX_WORD]; printf("Input word: "); fgets(word, MAX_WORD, stdin); printf("\nWord square is:\n"); int i = 0; while (i < strlen(word) - 1) { printf("%s", word); i++; } return 0; } https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

exercise (●◌◌):

Print out a string in lower case For this activity, you'll be writing the function string_to_lower . It takes a string and converts it to lower case.

Download string_to_lower.c here, or copy it to your CSE account using the following command: $ cp -n /web/cs1511/22T1/activities/string_to_lower/string_to_lower.c .

Your task is to add code to this function in string_to_lower.c: // Convert the characters in `buffer` to lower case void string_to_lower(char *string) { // YOUR CODE GOES HERE! } string_to_lower.c also contains a simple main function to help you test your solution.

int main(void) { char str[MAX_LEN] = "Hi, mY nAmE iS sPonGEbOb sQuArePanTS."; string_to_lower(str); printf("%s\n", str); return 0; }

Your string_to_lower function will be called directly in marking. The main function is only to let you test your string_to_lower function.

Here is how string_to_lower.c should behave after you add the correct code to the function string_to_lower : $ dcc string_to_lower.c -o string_to_lower $ ./string_to_lower hi, my name is spongebob squarepants.

You can run an automated code style checker using the following command: $ 1511 style string_to_lower.c

When you think your program is working, you can use autotest to run some simple automated tests: $ 1511 autotest string_to_lower

When you are finished working on this exercise, you and your lab partner must both submit your work by running give : $ give cs1511 lab07_string_to_lower string_to_lower.c

Note, even though this is a pair exercise, you both must run give from your own account before Monday 04 April 20:00 to obtain the marks for this lab exercise.

Sample solution for string_to_lower.c

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

// convert a string to lowercase // a sample solution. #include <stdio.h> #define MAX_LEN 1024 void string_to_lower(char *buffer); int lowercase(int c); int main(void) { // NOTE: THIS WON'T WORK: // char *str = "Hello!" // string_to_lower(str) // // str only points to a string literal, which it is not legal to change. // If you attempt to modify it on Linux you will get a runtime error. // Instead, you need to create an array to store the string in, e.g.: // // char str[] = "Hello!" // string_to_lower(str) char str[MAX_LEN] = "Seventeen... string_to_lower(str); printf("%s\n", str);

SEVENTEEN, I SAY!";

return 0; } // Convert the characters in `buffer` to lower case void string_to_lower(char *buffer) { int i = 0; while (buffer[i] != '\0') { buffer[i] = lowercase(buffer[i]); i = i + 1; } } int lowercase(int c) { if (c >= 'A' && c <= 'Z') { return c - 'A' + 'a'; } else { return c; } }

exercise (●●◌):

Encrypting Text with a Caesar Cipher Write a C program caesar.c which reads characters from its input and writes the characters to its output encrypted with a Caesar cipher.

A Caesar cipher shifts each letter a certain number of positions in the alphabet.

The number of positions to shift must first be scanned in from the terminal.

Characters other than letters should not be encrypted.

Your program should stop only at the end of input.

Your program should contain at least one function other than main.

HINT:

Be careful when using fgets to read in after a scanf! There'll be a newline still left in the standard input which fgets sees, and stops on - meaning you won't read in what's after. It's a good idea to remove this using some whitespace in the scanf: https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

scanf("%d ", &shift) . Or, use a different way of reading than fgets.

For example: $ ./caesar 1 This life well it's slipping right through my hands Uijt mjgf xfmm ju't tmjqqjoh sjhiu uispvhi nz iboet These days turned out nothing like I had planned Uiftf ebzt uvsofe pvu opuijoh mjlf J ibe qmboofe Ctrl-D $ ./caesar 10 abcdefghijklmnopqrstuvwxyz klmnopqrstuvwxyzabcdefghij ABCDEFGHIJKLMNOPQRSTUVWXYZ KLMNOPQRSTUVWXYZABCDEFGHIJ Ctrl-D $ ./caesar -42 Control well it's slipping right through my hands Myxdbyv govv sd'c cvszzsxq bsqrd drbyeqr wi rkxnc These days?

Droco nkic?

Ctrl-D

HINT:

Want a more visual Example? Play around with the below visual by adding your own shift and testing out different letters!

Caesar Cipher Visual Shift 0

Input

Output ----->

a

w

x

y

z

a

a

b

c

d

a

a

b

b

c

c

d

d

e

e

f

f

g

g

h

h

i

i

j

j

k

k

l

l

m

e

v

n

f

----->

m n

o

o

p

p

u

g

q

q

t

h

r

r

s

s

t

t

u

u

v

v

w

w

x

x

y

y

z

z

i

s r

q

p

o

n m

l

k

j

Hint: handle upper and lower case letters separately Hint: use % (moduluo) > what does this operator return?

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

Hint: use % (moduluo) -> what does this operator return?

Hint: create a function with a prototype like this: char encrypt(char character, int shift);

which returns the character shifted by the specified amount

Manually Cracking a Caesar Cipher Here is some (New Zealand) English text that has been encrypted with a Caesar cipher.

Z uf dp drbvlg ze jfdvsfup vcjv'j tri Nv fiuvi uzwwvivek uizebj rk kyv jrdv srij Z befn rsflk nyrk pfl uzu reu Z nreer jtivrd kyv kilky Jyv kyzebj pfl cfmv kyv svrty, pfl'iv jlty r urde czri

Use the program you have just written to discover the secret text?

Hint:: try different shifts until you see English.

Shift: 17 I do my makeup in somebody else's car We order different drinks at the same bars I know about what you did and I wanna scream the truth She thinks you love the beach, you're such a damn liar

You program will only be tested with an appropriate and valid mapping input for marking - but a good programmer would check the input is present and appropriate.

You can run an automated code style checker using the following command: $ 1511 style caesar.c

When you think your program is working, you can use autotest to run some simple automated tests: $ 1511 autotest caesar

When you are finished working on this exercise, you and your lab partner must both submit your work by running give : $ give cs1511 lab07_caesar caesar.c

Note, even though this is a pair exercise, you both must run give from your own account before Monday 04 April 20:00 to obtain the marks for this lab exercise.

Sample solution for caesar.c

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

// //

Written 3/3/2018 by Andrew Taylor (andrewt@unsw.edu.au) Write stdin to stdout encrypted with a Caesar Cipher

//

https://en.wikipedia.org/wiki/Caesar_cipher

// #include <stdio.h> #include <stdlib.h> #define ALPHABET_SIZE

26

int encrypt(int character, int shift); int main(void) { int shift; scanf(" %d", &shift); // removes trailing newline getchar(); // negative shifts need to be converted to the equivalent positive shift if (shift < 0) { shift = ALPHABET_SIZE + (shift % ALPHABET_SIZE); } int character = getchar(); while (character != EOF) { int encrypted_character = encrypt(character, shift); putchar(encrypted_character); character = getchar(); } return 0; } // encrypt letters with a caesar cipher with the specified shift // the specified characters is returned shifted the specified number of positions // characters other than letters are returned unchanged int encrypt(int character, int shift) { if (character >= 'A' && character <= 'Z') { return 'A' + (character - 'A' + shift) % ALPHABET_SIZE; } else if (character >= 'a' && character <= 'z') { return 'a' + (character - 'a' + shift) % ALPHABET_SIZE; } else { return character; } }

exercise (●●◌):

Encrypting Text with a Substitution Cipher Write a C program substitution.c which reads characters from its input and writes the characters to its output encrypted with a Substitution cipher.

A Substitution cipher maps each letter to another letter.

The mapping will be given to your program as the first input (no spaces between any characters). This is all on one line. This input will contain 26 characters: an ordering of the letters 'a'..'z'.

Characters other than letters should not be encrypted.

Your program should stop only at the end of input.

Your program should contain at least one function other than main.

HINT:

B

f l

i

i th

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

i

th

b

t

li

dt

d

di

h

'

d it i

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

Be careful scanning in the mapping - there may be an extra newline you need to remove depending how you've read it in.

For example: $ ./substitution Enter mapping: qwertyuiopasdfghjklzxcvbnm Enter text: I was scared of dentists and the dark O vql leqktr gy rtfzolzl qfr zit rqka I was scared of pretty girls and starting conversations O vql leqktr gy hktzzn uoksl qfr lzqkzofu egfctklqzogfl Ctrl-D $ ./substitution Enter mapping: abcdefghijklmnopqrstuvwxyz Enter text: The identity cipher!!!

The identity cipher!!!

Ctrl-D $ ./substitution Enter mapping: bcdefghijklmnopqrstuvwxyza Enter text: The Caesar cipher is a subset of the substitution cipher!

Uif Dbftbs djqifs jt b tvctfu pg uif tvctujuvujpo djqifs!

Ctrl-D

Your program will only be tested with an appropriate and valid mapping input for marking - but a good programmer would check the input is present and appropriate.

You can run an automated code style checker using the following command: $ 1511 style substitution.c

When you think your program is working, you can use autotest to run some simple automated tests: $ 1511 autotest substitution

When you are finished working on this exercise, you and your lab partner must both submit your work by running give : $ give cs1511 lab07_substitution substitution.c

Note, even though this is a pair exercise, you both must run give from your own account before Monday 04 April 20:00 to obtain the marks for this lab exercise.

Sample solution for substitution.c

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

//

Written 3/3/2018 by Andrew Taylor (andrewt@unsw.edu.au)

// //

Write stdin to stdout encrypted with a Substitution cipher https://en.wikipedia.org/wiki/Substitution_cipher

// //

The mapping will be supplied as a command-line argument containing 26 characters:

//

These will be an an ordering of the letters 'a'..'z'.

#include <stdio.h> #include <string.h> #define ALPHABET_SIZE

26

int encrypt(int character, char mapping[ALPHABET_SIZE]); int main(void) { printf("Enter mapping:\n"); char mapping[ALPHABET_SIZE + 1] = {0}; int i = 0; while (i < ALPHABET_SIZE) { mapping[i] = getchar(); i++; } mapping[ALPHABET_SIZE] = '\0'; // There's still a trailing newline in stdin after our mapping we need to remove getchar();

// Error checking - not necessary in student solution or tested if (mapping[0] == '\0') { printf("Usage: ./substitution <mapping>\n"); return 1; } if (strlen(mapping) != ALPHABET_SIZE) { printf("./substitution: mapping must contain %d letters\n", ALPHABET_SIZE); return 1; } printf("Enter text:\n"); int character = getchar(); while (character != EOF) { int encrypted_character = encrypt(character, mapping); putchar(encrypted_character); character = getchar(); } return 0; } // encrypt letters with a substitution cipher with the specified mapping int encrypt(int character, char mapping[ALPHABET_SIZE]) { if (character >= 'A' && character <= 'Z') { return mapping[character - 'A'] - 'a' + 'A'; } else if (character >= 'a' && character <= 'z') { return mapping[character - 'a']; } else { return character; } }

exercise (●●●):

Decrypting a Substitution Cipher Write a C program decode.c which decrypts text encrypted by substitution.c The structure is very similar to the above exercise substitution only working backwards

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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substitution, only working backwards.

COMP1511 22T1 — Week 07 Laboratory Sample Solutions

You are allowed to reuse code you've written yourself in previous exercises.

HINT:

It is a good idea to draw on paper how the letters relate.

Remember: the first letter in the mapping is what 'a' has already been replaced by, the second for 'b', third for 'c' and so on...

For example: $ ./decode Enter mapping: qwertyuiopasdfghjklzxcvbnm Enter text: O vql leqktr gy rtfzolzl qfr zit rqka I was scared of dentists and the dark O vql leqktr gy hktzzn uoksl qfr lzqkzofu egfctklqzogfl I was scared of pretty girls and starting conversations Ctrl-D $ ./decode Enter mapping: abcdefghijklmnopqrstuvwxyz Enter text: The identity cipher!!!

The identity cipher!!!

Ctrl-D $ ./decode Enter mapping: bcdefghijklmnopqrstuvwxyza Enter text: Uif Dbftbs djqifs jt b tvctfu pg uif tvctujuvujpo djqifs!

The Caesar cipher is a subset of the substitution cipher!

Ctrl-D

Your program will only be tested with an appropriate mapping input - but a good programmer would check the mapping is present and appropriate.

Manually Cracking a Substitution Cipher (NOTE: This is just for fun and theoretical purposes, not necessary to do this manually, only the program above!) This English text was encrypted with a substitution cipher.

Di jd, vdl'ht xtqa dh O qn Vdl rdlwk O'ss wdkith htqromu omkd ok O fhdwqwsv xdm'k Styk kd nv dxm rtzoetj Wlk kiqk'j kit royythtmet om dlh dfomodmj Vdl'ht q ndlkiyls Kiqk qndlmkj ydh qmdkith xtta dm nv dxm Mdx O'n q mdzts nqrt htjdlhetyls O jkqhk q eiqom xoki nv kidluik Kqsa oj eitqf, nv rqhsomu Xitm vdl'ht yttsomu houik qk idnt O xqmmq nqat vdl ndzt xoki edmyortmet O xqmmq wt xoki vdl qsdmt

What was the original text?

Hint: use frequency_analysis.c on the encrypted text and compare the frequencies to English letter frequencies and then try your guesses with decode.c Mapping: qwertyuiopasnmdfghjklzxcvb

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

Oh so, you're weak or I am You doubt I'll bother reading into it I probably won't Left to my own devices But that's the difference in our opinions You're a mouthful That amounts for another week on my own Now I'm a novel made resourceful I start a chain with my thought Talk is cheap, my darling When you're feeling right at home I wanna make you move with confidence I wanna be with you alone

You can run an automated code style checker using the following command: $ 1511 style decode.c

When you think your program is working, you can use autotest to run some simple automated tests: $ 1511 autotest decode

When you are finished working on this exercise, you and your lab partner must both submit your work by running give : $ give cs1511 lab07_decode decode.c

Note, even though this is a pair exercise, you both must run give from your own account before Monday 04 April 20:00 to obtain the marks for this lab exercise.

Sample solution for decode.c

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

//

Written 3/3/2018 by Andrew Taylor (andrewt@unsw.edu.au)

// //

Write stdin to stdout decrypted with a Substitution cipher https://en.wikipedia.org/wiki/Substitution_cipher

// // The mapping used to encrypt the input // will be supplied as a command-line argument containing 26 characters: // These will be an an ordering of the letters 'a'..'z'. #include <stdio.h> #include <string.h> #include <assert.h> #define ALPHABET_SIZE 26 void compute_inverse_mapping(char mapping[ALPHABET_SIZE], char inverse_mapping[ALPHABET_SIZE]); int decrypt(int character, char

inverse_mapping[ALPHABET_SIZE]);

int main(void) { char inverse_mapping[ALPHABET_SIZE] = {0}; printf("Enter mapping:\n"); char mapping[ALPHABET_SIZE + 1] = {0}; int i = 0; while (i < ALPHABET_SIZE) { mapping[i] = getchar(); i++; } mapping[ALPHABET_SIZE] = '\0'; // There's still a trailing newline in stdin after our mapping we need to remove getchar();

// Error checking - not necessary in student solution or tested if (mapping[0] == '\0') { printf("Usage: ./decode <mapping>\n"); return 1; } if (strlen(mapping) != ALPHABET_SIZE) { printf("./decode: mapping must contain %d letters\n", ALPHABET_SIZE); return 1; } printf("Enter text:\n"); compute_inverse_mapping(mapping, inverse_mapping); int character = getchar(); while (character != EOF) { int decrypted_character = decrypt(character, inverse_mapping); putchar(decrypted_character); character = getchar(); } return 0; }

// mapping must contain an ordering of letters 'a'..'z' // the inverse_mapping will be stored in inverse_mapping void compute_inverse_mapping(char mapping[ALPHABET_SIZE], char inverse_mapping[ALPHABET_SIZE]) { int i = 0; while (i < ALPHABET_SIZE) { int character = mapping[i]; assert(character >= 'a' && character <= 'z'); inverse_mapping[character - 'a'] = 'a' + i; i = i + 1; } } https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

// decrypt letters with a substitution cipher with the specified inverse_mapping int decrypt(int character, char inverse_mapping[ALPHABET_SIZE]) { if (character >= 'A' && character <= 'Z') { return inverse_mapping[character - 'A'] - 'a' + 'A'; } else if (character >= 'a' && character <= 'z') { return inverse_mapping[character - 'a']; } else { return character; } }

exercise (☠):

Solving a 3D word search Write a C program word_search.c which takes in as input from terminal: A number n followed by any number of words An nxnxn cube of characters

3D Arrays Note 3D arrays are outside the scope of this course. The use of them in this exercise is simply to allow those that are interested to use/explore them.

Reminder: This exercise is not worth any marks, so do not feel obliged to learn things that aren't in this course!

Before reading any further, it is important to note that you will be expected to use 3D arrays in this exercise (although it is possible without them). A small snippet on how to create a 3d array is shown below. #include <stdio.h> #define X_SIZE 5 #define Y_SIZE 3 #define Z_SIZE 7 int main(void) { // Declaring a 3D array of integers and initialising all elements to 0 int cube[X_SIZE][Y_SIZE][Z_SIZE] = {0}; // Filling element at index (2, 1, 5) with value '6' cube[2][1][5] = 6; // Printing this value printf("%d", cube[2][1][6]); }

A 3D array can be thought of in a couple of ways A Rectangular prism made up of small cubes (each array element) An array of 2D arrays (array of grids) An array of arrays of arrays (Rolls right off the tongue) A CPU's nightmare In this exercise, there is a cube which represents a 3D word search grid. This cube is filled in by from values scanned in when the program is actually run. Your goal is to determine whether each of the provided words in the given input arguments can be found within this cube.

The rules for finding a word are as follows: Words can only appear in straight lines in the cube Words will only be going through one dimension of the cube, this means if a word is found through the x dimension, all characters in that word will have the same y and z positions Words cannot exist as diagonals https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

Words will not appear backwards. This means that words can only be found when going through each dimension. In terms of how this would work with a 3D array, you will never need to go backwards from an index when searching for a word Here are some examples of what the programming is expected to do:

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

$ ./word_search Please enter cube length: 2 Please enter grid 0: oa np Please enter grid 1: on ai on on found! an an found! po po not found! pi pi found! ai ai found! pa pa not found!

Ctrl-D $ ./word_search Please enter cube length: 3 Please enter grid 0: daa ood gwd Please enter grid 1: opb pda pod Please enter grid 2: opo edm sup dog dog found! doge doge not found! cat cat not found! ood ood found! add add found! friend friend not found! app app found! op op found! man man not found! bad bad found! long long not found! dam dam found! supercalifragilisticexpialidocious supercalifragilisticexpialidocious not found! low low not found! woo woo not found! moo moo not found! pod pod found! https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

lip lip not found!

Ctrl-D

Assumptions You will always be given an integer as the first input.

All inputs will be valid.

The cube size that is input will be in the range [1, 32] inclusive.

You can run an automated code style checker using the following command: $ 1511 style word_search.c

When you think your program is working, you can use autotest to run some simple automated tests: $ 1511 autotest word_search

When you are finished working on this exercise, you and your lab partner must both submit your work by running give : $ give cs1511 lab07_word_search word_search.c

Note, even though this is a pair exercise, you both must run give from your own account before Monday 04 April 20:00 to obtain the marks for this lab exercise.

Sample solution for word_search.c

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

// Program to take in a list of words then scan in a 3D cube of letters then // print out the words that are found in this cube // Written by Rory Golledge (z5308772) on October 2021 #include <stdio.h> #include <stdlib.h> #include <string.h> #define WORD_LEN 50 #define MAX_SIZE 32 #define TRUE 1 #define FALSE 0 void fill_cube(int size, int search_cube[size][size][size]); int word_in_cube(char *word, int size, int search_cube[size][size][size]); int find_word_from_index( char *word, int x, int y, int z, int size, int search_cube[size][size][size] ); int word_at_index( char *word, int *x, int *y, int *z, int *target_dimension, int size, int search_cube[size][size][size] ); int main(void) { int search_cube[MAX_SIZE][MAX_SIZE][MAX_SIZE] = {0}; int size; printf("Please enter cube length: "); scanf(" %d", &size); fill_cube(size, search_cube); getchar(); putchar('\n'); char word[WORD_LEN]; while (fgets(word, WORD_LEN, stdin) != NULL) { if (word[strlen(word) - 1] == '\n') { word[strlen(word) - 1] = '\0'; } if (word_in_cube(word, size, search_cube)) { printf("%s found!\n", word); } else { printf("%s not found!\n", word); } } return 0; } /* * Fills the search cube with given input from the user */ void fill_cube(int size, int search_cube[size][size][size]) { int x = 0; while (x < size) { printf("Please enter grid %d:\n", x); int y = 0; while (y < size) { int z = 0; while (z < size) { search_cube[x][y][z] = getchar(); // Ignore new lines if (search_cube[x][y][z] != '\n') { z++; } } https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

y++; } x++; } } /* * Determines if a given word is found in the search cube from the provided * rules. * * Returns TRUE if found, otherwise FALSE. */ int word_in_cube(char *word, int size, int search_cube[size][size][size]) { int x = 0; // This first loop can be thought of as holding each yz plane while (x < size) { int y = 0; // This second loop can be though of as holding each z strip while (y < size) { int z = 0; // And finally, this third loop is where all the magic happens as // each character can be indexed here. while (z < size) { if (find_word_from_index(word, x, y, z, size, search_cube)) { return TRUE; } z++; } y++; } x++; } return FALSE; } /* * Finds the given word by using the index (x, y, z) as a starting point. * Returns TRUE if found, otherwise FALSE */ int find_word_from_index( char *word, int x, int y, int z, int size, int search_cube[size][size][size] ) { return word_at_index(word, &x, &y, &z, &x, size, search_cube) || word_at_index(word, &x, &y, &z, &y, size, search_cube) || word_at_index(word, &x, &y, &z, &z, size, search_cube); } /* * Determines if the given word is found from the current index (x, y, z) when * looking at the target_dimension. * * The 'target_dimension' is a pointer with equal value to either x, y or z. * This is simply incremented in a loop and by doing it this way, there is no * need to check for 3 things to determine what to increment. * * Returns TRUE if found, otherwise FALSE */ int word_at_index( char *word, int *x, int *y, int *z, int *target_dimension, int size, int search_cube[size][size][size] ) { int word_length = strlen(word); // Cannot physically find the word when it there is not enough space if (*target_dimension + word_length > size) { return FALSE; } https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

// Just store what the original target was to maintain state int target = *target_dimension; int i = 0; while (word[i] != '\0' && search_cube[*x][*y][*z] == word[i]) { (*target_dimension)++; i++; } *target_dimension = target; if (i == word_length) { return TRUE; } return FALSE; }

Feedback Form NOTE:

Feedback!

We value our students' feedback and want your opinions to help improve the course. Please fill out this form below and leave any comments :) Feedback form here!

Submission When you are finished each exercises make sure you submit your work by running give .

You can run give multiple times. Only your last submission will be marked.

Don't submit any exercises you haven't attempted.

If you are working at home, you may find it more convenient to upload your work via give's web interface.

Remember you have until Week 8 Monday 20:00 to submit your work.

You cannot obtain marks by e-mailing your code to tutors or lecturers.

You check the files you have submitted here.

Automarking will be run by the lecturer several days after the submission deadline, using test cases different to those autotest runs for you. (Hint: do your own testing as well as running autotest .)

After automarking is run by the lecturer you can view your results here. The resulting mark will also be available via give's web interface.

Lab Marks When all components of a lab are automarked you should be able to view the the marks via give's web interface or by running this command on a CSE machine: $ 1511 classrun -sturec

COMP1511 22T1: Programming Fundamentals is brought to you by the School of Computer Science and Engineering at the University of New South Wales, Sydney.

For all enquiries, please email the class account at cs1511@cse.unsw.edu.au https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

CRICOS P

id

00098G

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COMP1511 22T1 — Week 07 Laboratory Sample Solutions

CRICOS Provider 00098G

https://cgi.cse.unsw.edu.au/~cs1511/22T1/lab/07/answers

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