Description
In this lab, you will be writing programs that use functions and pointers. This lab will be
due in the your lab section in the week of February 11, 2019.
For each part in this lab, you should write your own main function to exercise the functions
you have written with different parameter values. The functions should be by themselves
in a file—there should not be a main function in the file.
Part 1 – Data Encryption
Data Encryption is the process of transforming data, using a cipher, to make it unreadable
to anyone except those possessing special knowledge. In this problem you will implement
a simple encryption technique on data that comprises of non-negative integers that have
at least six digits with no leading zeroes. In order to encrypt the number the following
functions are to be implemented:
void input(int *num);
int add4(int num);
int shift(int num);
void printOutput(int encryptNum, int originalNum);
The function input is used to read a positive integer having at least six digits and store it in
the variable num. All leading zeroes in the input are neglected and are not counted as valid
digits. The function will continue requesting for a number until a valid input is provided
by the user.
A sample run of the function is shown below with data entered by the user displayed using bold font.
Please enter an integer greater than 99999: 2348
Incorrect input.
Please enter an integer greater than 99999: 012345
Incorrect input.
Please enter an integer greater than 99999: 102345
The number entered is 102345
The functions add4 and shift are used to encrypt the number. First, modify the value of
each digit of num by adding 4 to the digit. The function add4 modifies the value of each
digit of num by adding 4 to each digit, and returns the modified number. Due to addition, if
the value of any digit is greater than 9 then subtract 10 from the number so that each digit
ranges between 0 and 9. For example, if num is 345678 then add4 should return 789012.
Note that the number of digits of the modified number returned by add4 can be less than
the number of digits in num. For example, if num is 665325, then add4 returns 009769, which
is really 9769.
The input (num) of the function shift is the modified number (output of the function add4).
The function shift shifts the position of each digit to the left by one place. The most significant digit becomes the least significant digit. For example, if the input (num) is 567890 then
the output of the function shift is 678905. The modified value is returned by shift and
is the final encrypted number. Similar to add4 function, the number of digits returned by
shift can be less than the number of digits in num (input to function shift). For example,
if num is 107982, then the encrypted number is 79821.
The function printOutput prints the original number (originalNum) and the encrypted
number (encryptNum). Refer to the examples below for the output format.
You are allowed to use the math.h functions in your solution. Remember to add -lm to
your gcc command line.
Shown below are example runs of the program with data entered by the user displayed
using bold font. Given the same user input, your output should match the output exactly,
including all punctuation. Any variation from this will result in loss of marks.
• Example 1:
Please enter an integer greater than 99999: 4569012
The number entered is 4569012
Original number: 4569012
Encrypted number: 9034568
• Example 2:
Please enter an integer greater than 99999: 563918
The number entered is 563918
Original number: 563918
Encrypted number: 73529
• Example 3:
Please enter an integer greater than 99999: 70912
Incorrect input.
Please enter an integer greater than 99999: 093679
Incorrect input.
Please enter an integer greater than 99999: 0877893
The number entered is 877893
Original number: 877893
Encrypted number: 112372
Note: The encrypted number can have less than 6 digits (as shown in Example 2). It is
up to the decryption technique to handle this (not part of this problem). In the case of
Example 3, 0877893 is a valid input as it has 6 digits without any leading zero (877893).
When you are ready to submit your work, place all of your functions in a file named
Lab5Part1.c (with no main function) for submission.
Part 2 – Craps
In this problem you will implement the popular dice game craps. The following is a brief
description of how the game is played.
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The game of craps is played with two dice. On the first roll, the player wins if the sum
of the dice is 7 or 11. The player loses if the sum is 2, 3, or 12. Any other roll is called
a “point” and the game continues. On each subsequent roll, the player wins if he or she
rolls the point again. The player loses by rolling 7. Any other roll is ignored and the game
continues. At the end of the game the user has a choice to start a new game by pressing
y or Y. Pressing any other key will display the number of wins and losses and then exit
the program. A sample run of the program is shown below with data entered by the user
displayed using bold font. Your program output will look exactly as below when you run
your program in one of the ECF machines with the matching user inputs.
You rolled: 7
You win!
Play again? y
You rolled: 6
Your point is: 6
You rolled: 8
You rolled: 6
You win!
Play again? y
You rolled: 6
Your point is: 6
You rolled: 5
You rolled: 5
You rolled: 11
You rolled: 2
You rolled: 10
You rolled: 9
You rolled: 8
You rolled: 6
You win!
Play again? Y
You rolled: 5
Your point is: 5
You rolled: 4
You rolled: 7
You lose!
Play again? n
Wins: 3
Losses: 1
Write the following functions with the corresponding prototypes.
int rollDice(void);
bool playGame(void);
void winLoss(void);
The function rollDice should generate two random numbers, each between 1 and 6, and
return their sum. Use the rand function for rolling each dice to obtain a number between
1 and 6, inclusive. You are not allowed to use the function srand(). If you use it, you
will receive zero marks for this problem. The function rollDice is used to determine the
outcome of each dice roll.
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The function playGame should play one craps game. It returns true if the player wins and
false if the player loses. For every game of crap, the function playGame calls the function
rollDice one or more times, depending upon the value returned by rollDice. playGame is
also responsible for displaying messages showing results of the player’s dice rolls.
The function winLoss keeps track of the number of wins and losses in one session. It
repeatedly calls the function playGame until the user requests to end the program. winLoss
should also report the number of wins and losses before it ends.
When you are ready to submit your work, place all of your functions in a file named
Lab5Part2.c (with no main function) for submission.
Part 3 – Zeller’s Algorithm
In 1883, German mathematician Christian Zeller devised an algorithm, popularly known
as Zeller’s congruence, to calculate the day of the week on which a given date will fall or
fell. In this exercise you will implement the following two functions:
void inputDate(int *day, int *month, int *year);
void calculateDay(int day, int month, int year);
The user must enter the date as dd/mm/yyyy and the function inputDate stores it in the
variables day,month and year. Assume that the user enters a valid date.
The function calculateDay will calculate the day of the week and print it. First, the month
of the year must be transformed as an integer between 1–12 where March is 1 and February
is 12. Thus, if the month is Jan or Feb, the year must also be modified to the previous
year (see examples below). Zeller’s algorithm is defined as follows:
Let A, B, C, D denote integer variables that have the following values:
A = the month of the year, with March having the value 1, April the value 2,. . . , December the value 10, and January and February being counted as months 11 and 12 of the
preceding year (in which case, subtract 1 from C)
B = the day of the month (1, 2, 3,. . . , 30, 31)
C = the year of the century (e.g. C = 89 for the year 1989)
D = the century (e.g. D = 19 for the year 1989)
The following examples show the values of A, B, C, D for a given date.
• Example 1: For input date 5/12/2006
A = 10, B = 5, C = 6, D = 20
• Example 2: For input date 03/02/1974
A = 12, B = 3, C = 73, D = 19
• Example 3: For input date 8/1/2000
A = 11, B = 8, C = 99, D = 19
• Example 4: For input date 18/3/2020
A = 1, B = 18, C = 20, D = 20
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Let W, X, Y, Z, R also denote integer variables. Compute their values in the following order
using integer arithmetic:
W = (13*A – 1) / 5
X = C / 4
Y = D / 4
Z = W + X + Y + B + C – 2*D
R = the remainder when Z is divided by 7
If the value of R is negative, then add 7 to it. At the end of the computation R is a number
between 0 and 6 and is the day of the week, where 0 represents Sunday, 1 is Monday,. . . ,
6 is Saturday. Shown below are example runs of the program. Given the same user input,
your output should match the output exactly, including all punctuation. Any variation
from this will result in loss of marks.
• Example 1:
Please enter a date: 10/10/2012
The day 10/10/2012 is a Wednesday.
• Example 2:
Please enter a date: 05/02/1985
The day 5/2/1985 is a Tuesday.
When you are ready to submit your work, place all of your functions in a file named
Lab5Part3.c (with no main function) for submission.
Submission Instructions
There are ten (10) marks available in this lab.
TA Grading (4 marks)
Your solution will be marked by a Teaching Assistant during your scheduled lab period for
programming style and your understanding of the code. You can discuss programming
style with your TA and on Piazza. Here are some quick guidelines:
• Good choices for variable names that indicate their purpose.
• A consistent naming convention. Use camelCase for normal variable names.
• Comments that explain code that is difficult to understand.
• Proper indentation.
• Appropriate white space between lines for better readability.
• A limited number of, or ideally zero, global variables.
Automated Grading (6 marks)
Your solution must be submitted electronically by the end of your scheduled lab period.
Submission of the lab requires you to use a terminal. In the terminal, you must:
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1. Go to the directory that contains Lab5Part1.c, Lab5Part2.c, and Lab5Part3.c (i.e.,
use the cd command in the terminal).
2. Type in the following command: /share/copy/aps105s/lab5/submit
This command will run an exercise program that will check to make sure everything looks
okay. If it finds a problem, it will ask you if you are sure that you want to submit.
Note that you may submit your work as many times as you want prior to the deadline;
only the most recent submission is marked. You can also run the exerciser on your own
with the following command:
/share/copy/aps105s/lab5/exercise
Finally, you can also check to see if what you think you have submitted is actually there,
for peace of mind, using the following command:
/share/copy/aps105s/lab5/viewsubmitted
Obtaining Your Automated Grade
After all lab sections have finished, a short time later, you will be able to run the automarker to determine the auto-marked fraction of your grade on the code you have submitted. To do so run the following command:
/share/copy/aps105s/lab5/marker
This command will compile and run your code and test it with all the test cases used to
determine the auto-mark grade. You will be able to see those test cases’ output and what
went right or wrong.
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