Description
Q1. Write a Line class to represent a line in a 2D plane. The class has two data members defining a line, a slope and an intercept. It must not have
any other data members. It should have the following public methods:
A constructor taking a slope and an intercept value to make a new line
A constructor that takes a set of point coordinate values x1, y1, x2, y2, which define a line passing through the points (x1,y1) and (x2,y2)
A method double distanceTo(Point p) which returns the distance between the line and a given point object p
A method Point intersection(Line ln) which returns the intersection point of this line and a given line ln.
Use the Point class given below for the Point type needed in the last two methods (put it in your code before your Line class). Do not modify this
Point class.
class Point {
private:
double x, y;
public:
Point(double _x, double _y) : x(_x), y(_y) {}
double _x() { return x; }
double _y() { return y; }
double distanceTo(const Point & p) { return sqrt((x-p.x)*(x-p.x) + (y-p.y)*(y-p.y)); }
};
Note: you may use the fabs() and sqrt() methods from the standard maths library.
[15 marks]
Q2. Write a function (not a method of a class), that uses the functionality already provided by your Line class, to solve any pair of simultaneous
equations of the form:
a x + b y + c = 0
a x + b y + c = 0
Your function should have the following form:
Point solve(double a1, double b1, double c1, double a2, double b2, double c2) { /* use Line objects here to find the answer – don’t
rewrite any code unnecessarily */ }
Test your method using the following code in main() :
Point sol = solve(2.5, -2.0, 3.0, 1.5, -3.0, -4.1);
cout << “Equations solution is x = ” << sol._x() << ” and y = ” << sol._y() << endl;
which should print out
Equations solution is x = -3.82222 and y = -3.27778
Note: Aim to have no more than 3 or 4 lines of code in your function.
1 1 1
2 2 2
14/08/2020 2020_EE219: Assignment 4
https://loop.dcu.ie/mod/assign/view.php?id=1227277 2/6
[15 marks]
Note: In the next three questions you will create a set of classes that are related by inheritance. It is recommended that you read all three questions
before writing any code. Sketching out a class diagram as you read the questions will help you to get a picture of the required structure of the
classes (you do not need to submit this diagram).
Q3. Write an abstract class to represent a Student. A student has an ID, a first name and a last name. The ID should be an integer and the first
and last names should be C++ strings. The class must have the following methods:
A constructor that takes a student ID value, a first name and a last name
A int getID() method which returns the student’s ID value
A pure virtual method string getType() which, if implemented in any class derived from Student, would be expected to return the type of
student as a string
A virtual void printInfo() method which prints out the student’s details. This method should call the getType() method to print out the student
type as the first line of the printout.
[10 marks]
Q4. Write a concrete class called ResearchStudent which inherits from your Student class of question 3. A research student has a supervisor name
(as a single C++ string) and a thesis title (as a C++ string). The class must also have the following methods:
A constructor taking the student’s ID, first and last names, supervisor name and thesis title. This constructor calls the parent class constructor.
A void printInfo() method that calls the parent class’s printInfo() method to print generic student information and also prints details specific to
a research student.
A method that provides an implementation (overrides) the base class pure virtual function getType(). This method should simply return the
string “Research Student”.
[15 marks]
Q5. Write a concrete class called TaughtStudent which also inherits from your Student class. A taught student has an array of module names for
which they are registered. This array can have up to 10 module names. A module name is a C++ string. Additionally, the class has a
member numRegisteredModules which stores the number of modules for which the student is currently registered. The class must have the
following methods:
A constructor taking the student’s ID, first and last name. The constructor should set numRegisteredModules to 0.
A method bool registerFor(const string & moduleName) which adds a module to the student’s modules. If the student is already registered
for 10 modules then this method should return false, otherwise it returns true.
A void printInfo() method that calls the parent class printInfo() method and also prints details specific to a taught student, including their list of
registered modules.
An override for the base class pure virtual function that returns the string “Taught Student”.
[15 marks]
Q6. Write a function (not a method of a class) void studentTester() which contains code to test the classes you have developed in the previous
three questions. When this function is called it should:
Create two research students.
Create two taught students, and register them for three modules each.
Make an array of pointers to Student and point the elements of the array at your four student objects.
Run a for loop which calls each student’s printInfo() method, using the array of pointers.
[15 marks]
Q7. Write a class Employee. An employee has a number and a name and the following additional features:
The first employee created is automatically assigned the number 1001, the second 1002 and so on. Implement this feature using a static data
member nextEmpolyeeNumber.
Also keep track of the total number of employee objects using another static data member totalNumberEmployees. Note that this number
should be decremented when an Employee object is destroyed.
Add a static member function called numEmpolyees() which returns the current number of employee objects.
Using the following code in main(), explain why this code “leaks memory”.
