Riyadh Philanthropic Society For Science
Prince Sultan College For Woman
Dept. of Computer & Information Sciences
CS 102
Computer Programming II
(Lab: Defining Classes)
Exercise
Complete the five missing parts in the following program:
#include<iostream>
#include<cmath>
using namespace std;
class Loan
{
public:
Loan(double the_amount, double the_rate, int the_term);
Loan( );
void display( );
double payment( );
private:
double amount;
// $ amount of the loan
double rate;
// annual interest rate
int term;
// number of months, length of the loan
};
Lab: Defining Classes
continue
1
Exercise
int main( )
{
//1. Declare two loan objects: loan1 (initialized to given values) and
// loan2 (initialized to default values)
cout << "Display loan1: \n";
loan1.display();
//2. Display all information about loan2
cout << "Monthly payment of loan1 = " << loan1.payment() << endl;
loan2 = loan1;
cout << "Monthly payment of loan2 = " << loan2.payment() << endl;
return 0;
}
continue
Lab: Defining Classes
2
Exercise
Loan::Loan(double the_amount, double the_rate, int the_term)
{
//3. Initialize the loan amount to the_amount, the loan rate to the_rate
// and the loan term to the_term
}
//4. Write the definition of the default constructor and initialize all member
// variables to zero
void Loan::display()
{
//5. Display all information about the loan, i.e. amount, rate, and term
}
double Loan::payment()
{
double fraction_rate = rate / 1200;
return (amount * fraction_rate * (pow((fraction_rate + 1),term) /
(pow((fraction_rate+1),term) - 1)));
}
Lab: Defining Classes
3
Solution
#include<iostream>
#include<cmath>
using namespace std;
class Loan
{
public:
Loan(double the_amount, double the_rate, int the_term);
Loan( );
void display( );
double payment( );
private:
double amount;
// $ amount of the loan
double rate;
// annual interest rate
int term;
// number of months, length of the loan
};
continue
Lab: Defining Classes
4
Solution
int main( )
{
Loan loan1(1000,5,10), loan2;
cout << "Display loan1: \n";
loan1.display();
cout << "Display loan2: \n";
loan2.display();
cout << "Monthly payment of loan1 = " << loan1.payment() << endl;
loan2 = loan1;
cout << "Monthly payment of loan2 = " << loan2.payment() << endl;
return 0;
}
continue
Lab: Defining Classes
5
Solution
Loan::Loan(double the_amount, double the_rate, int the_term)
{
amount = the_amount;
rate = the_rate;
term = the_term;
}
Loan::Loan()
{
amount = 0;
rate = 0;
term = 0;
}
continue
Lab: Defining Classes
6
Solution
void Loan::display()
{
cout << "Amount = " << amount << endl
<< "Rate = " << rate << endl
<< "Term = " << term << endl;
}
double Loan::payment()
{
double fraction_rate = rate / 1200;
return (amount * fraction_rate * (pow((fraction_rate + 1),term) /
(pow((fraction_rate+1),term) - 1)));
}
Lab: Defining Classes
7
Exercise
Write a class called Rectangle that represents a rectangle as a pair of
double values - the rectangle length and width.
Your class should include the following member functions:
• A constructor with two arguments that sets the length and
width to the values specified by its arguments.
• A get_length function that gets the length of the rectangle.
• A get_width function that gets the width of the rectangle.
Note: test the class.
Lab: Defining Classes
8
Solution
#include<iostream>
using namespace std;
class Rectangle
{
public:
Rectangle(double the_length, double the_width);
double get_length();
double get_width();
private:
double length;
double width;
};
continue
Lab: Defining Classes
9
Solution
int main( )
{
Rectangle rectangle1(1,2);
cout << "Length of rectangle1 = " << rectangle1.get_length() << endl
<< "Width of rectangle1 = " << rectangle1.get_width() << endl;
return 0;
}
Rectangle::Rectangle(double the_length, double the_width)
{
length = the_length;
width = the_width;
}
continue
Lab: Defining Classes
10
Solution
double Rectangle::get_length()
{
return length;
}
double Rectangle::get_width()
{
return width;
}
Lab: Defining Classes
11
Exercise
Add the following member functions to the Rectangle class:
• A default constructor that sets the length and width to 0.0.
• An area function that returns the area of the rectangle.
(length times width)
• A perimeter function that returns the perimeter of the rectangle.
(2 times length plus 2 times width)
Note: test the new functions.
Lab: Defining Classes
12
Solution
#include<iostream>
using namespace std;
class Rectangle
{
public:
Rectangle(double the_length, double the_width);
Rectangle( );
double get_length();
double get_width();
double area();
double perimeter();
private:
double length;
double width;
};
continue
Lab: Defining Classes
13
Solution
int main( )
{
Rectangle rectangle1(1,2), rectangle2;
cout << "Length of rectangle1 = " << rectangle1.get_length() << endl
<< "Width of rectangle1 = " << rectangle1.get_width() << endl;
cout << "Length of rectangle2 = " << rectangle2.get_length() << endl
<< "Width of rectangle2 = " << rectangle2.get_width() << endl;
double area = rectangle1.area();
double perimeter = rectangle1.perimeter();
cout << "Area of rectangle1 = " << area << endl
<< "Perimeter of rectangle1 = " << perimeter << endl;
return 0;
}
continue
Lab: Defining Classes
14
Solution
Rectangle::Rectangle(double the_length, double the_width)
{
length = the_length;
width = the_width;
}
Rectangle::Rectangle( )
{
length = 0;
width = 0;
}
continue
Lab: Defining Classes
15
Solution
double Rectangle::get_length()
{
return length;
}
double Rectangle::get_width()
{
return width;
}
double Rectangle::area()
{
return length * width;
}
double Rectangle::perimeter()
{
return 2 * length + 2 * width;
}
Lab: Defining Classes
16