Assignment 3 on C and Ruby

COMP 348: Principles of Programming Languages
Assignment 3 on C and Ruby
Summer 2020, sections AA and AB

Contents
1 General Information 2
2 Introduction 2
3 Ground rules 2
4 Your Assignment 2
4.1 The C Programming Language . . . . . . . . . . . . . . . . . . . . . . . . . 3
4.2 Ruby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5 What to Submit 7
6 Grading Scheme 8
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1 General Information

Weight: 9% of the overall grade.
2 Introduction
This assignment covers both Ruby and The C Programming Language, imperative as well
as multi-paradigm programming.
3 Ground rules
You are allowed to work on a team of 3 students at most (including yourself). Each team
should designate a leader who will submit the assignment electronically. ONLY one copy of
the assignment is to be submitted.
This is an assessment exercise. You may not seek any assistance from others while expecting
to receive credit. (You must work strictly within your team). Failure to do so will
result in penalties or no credit.
4 Your Assignment
This assignment consists of two parts:
1. The C Programming Language,
2. Ruby.
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4.1 The C Programming Language
Q 1. Pointers
You know in Java, a called method from main can not change the value of an integer declared
in main. For example:
public static void main() {
int a = 3;
CallFun( some parameters );
System.out.println(a);
}
The above code will always print 3 on the screen no matter what happens in CallFun or its
arguments.
Using pointers, rewrite the above program in C so that when CallFun is invoked the value
of a is changed to 17 in the main function. You need to pass only one parameter to CallFun.
You decide what that parameter is and what its type is.
Q 2. Pointers arithmetic & pointers to arrays and array elements
Use ONLY pointer arithmetic to implement the Selection Sort algorithm. You will also need
to implement DisplayArray function that takes an array as a parameter and the number of
elements it has and displays its content on the screen. The DisplayArray function should
ONLY use pointer arithmetic.
For example:
int main() {
int arr[5] = {1, 13, 5, 17, 11};
DisplayArray (arr, 5);
SelectionSort (arr);
DisplayArray (arr, 5);
}
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Output:
1, 13, 5, 17, 11
1, 5, 11, 13, 17
Q 3. Memory management and records
Create a struct to represent a Book. The book has a title of type char* and a price of type
oat. The main program reads the number of books n to store. Then the program creates
an array with exactly n elements.
The program then reads the information of each book and store them one by one in the
array.
Develop a function Display that takes an array of Book and the number of books in the
array. The Display function displays the content of the array on the screen.
Develop another function AverageBookPrice that takes an array of Book and the number
of books in the array and returns the average book price of all books in the array.
Develop a function Add that reads the info of a Book from the user and:
1. Expands the size of the array by 1
Hint: create a new array and copy all books from old to new. Do not forget to free
the old array
2. Adds the new book at the end of the newly created array
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4.2 Ruby
This section consists of three parts that are related, but may be implemented independently.
Q 4. Classes in Ruby
Dene the following class hierarchy in Ruby
1. Shape
(a) : the class constructors receives no parameter.
(b) : method print(): prints the name of the shape, perimeter, and area of the shape.
The name of the shape is the class name (i..e Shape for this class).
(c) : method perimeter(): default method to be implemented by child classes; returning nil by default.
(d) : method area(): default method to be implemented by child classes; returning
nil by default.
2. Circle
(a) : the class constructor receives the radius as the only parameter.
(b) : method perimeter(): overridden, returns the perimeter of the circle.
(c) : method area(): overridden, returns the area of the circle.
3. Rectangle
(a) : the class constructor receives the height and width of the rectangle.
(b) : method perimeter(): overridden, returns the perimeter of the rectangle.
(c) : method area(): overridden, returns the area of the rectangle.
4. Ellipse
(a) : the class constructor receives the semi-major and semi-minor axes (a and b).
(b) : method perimeter(): not to be implemented.
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(c) : method area(): overridden, returns the area of the ellipse (A = πab).
(d) : method eccentricity(): additional method that returns the eccentricity of the
ellipse (e =
√
a
2 − b
2
).
Q 5. File / Text Processing
Write a Ruby program that reads text le that contains the shape information (see previous
question). Every line in the text le consist of shape name and parameters to construct the
shape. The program create every shape and calls the print method and displays the result
on the screen. In case of errors (i.e. having negative values for sides, radius, etc.), and error
message may be displayed. An example given below:
Input:
shape
rectangle 10 20
rectangle 0 10
circle 2
ellipse 2 4
ellipse -1 4
Output:
Shape, perimeter: undefined, area: undefined
Rectangle, perimeter: 60, area: 200
Rectangle, perimeter: 0, area: 0
Circle, perimeter: 12.5663706144, area: 12.5663706144
Ellipse, perimeter: undefined, area: 25.1327412287
Error: Invalid Ellipse
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Q 6. Arrays and Hash
Extend the above program to display a statistics of the shapes after the text le is processes.
An example is given in the following
Output:
Statistics:
Shape(s): 5
Rectangle(s): 2
Circle(s): 1
Ellipse(s): 1
Use hashes to implement the above structure in memory.
Note that rectangles, circles, and ellipses are counted as shapes as well.
5 What to Submit
The assignment is to be submitted by the due date under the corresponding assignment box.
Your instructor will provide you with more details.
Submission Notes
Clearly include the names and student IDs of all members of the team in the submission.
Indicate the team leader.
IMPORTANT: You are allowed to work on a team of 3 students at most (including yourself).
Any teams of 4 or more students will result in 0 marks for all team members. If your work on
a team, ONLY one copy of the assignment is to be submitted. You must make sure that you
upload the assignment to the correct assignment box on Moodle. No email submissions are
accepted. Assignments uploaded to the wrong system, wrong folder, or submitted via email
will be discarded and no resubmission will be allowed. Make sure you can access Moodle
prior to the submission deadline. The deadline will not be extended.
Naming convention for uploaded le: Create one zip le, containing all needed les for your
assignment using the following naming convention. The zip le should be called a#_studids,
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where # is the number of the assignment, and studids is the list of student ids of all team
members, separated by (_). For example, for the rst assignment, student 12345678 would
submit a zip le named a1_12345678.zip. If you work on a team of two and your IDs are
12345678 and 34567890, you would submit a zip le named a1_12345678_34567890.zip.
Submit your assignment electronically on Moodle based on the instruction given by your
instructor as indicated above:
https://moodle.concordia.ca
Please see course outline for submission rules and format, as well as for the required demo
of the assignment. A working copy of the code and a sample output should be submitted
for the tasks that require them. A text le with answers to the dierent tasks should be
provided. Put it all in a le layout as explained below, archive it with any archiving and
compressing utility, such as WinZip, WinRAR, tar, gzip, bzip2, or others. You must keep
a record of your submission conrmation. This is your proof of submission, which you may
need should a submission problem arises.
6 Grading Scheme
Q1 4 marks
Q2 6 marks
Q3 10 marks
Q4 8 marks
Q5 8 marks
Q6 4 marks
Total: 40 marks.
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References
1. GCC: https://gcc.gnu.org/install/binaries.html
2. Online C compiler: https://www.onlinegdb.com/online_c_compiler
3. C string manipulation: https://en.wikibooks.org/wiki/C_Programming/String_
manipulation
4. https://en.wikipedia.org/wiki/Ellipse
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