1. OOP Lecture 5, 28th Feb, 2011
M. Anwar-ul-Haq
Question: Create a class Rectangle. The class has attributes length and width, each of
which defaults to 1.
It has member functions that calculate the perimeter and the area of the rectangle. It has
set and get functions for both length and width.
The set functions should verify that length and width are each floating-point numbers
larger than 0.0 and less than 20.0.
Solution:
#include <iostream>
using namespace std;
class Rectangle {
public:
Rectangle( double = 1.0, double = 1.0 );
double perimeter( void );
double area( void );
void setWidth( double w );
void setLength( double l );
double getWidth( void );
double getLength( void );
private:
double length;
double width;
};
Rectangle::Rectangle( double w, double l )
{ setWidth(w); setLength(l);}
double Rectangle::perimeter( void )
{
return 2 * ( width + length );
}
double Rectangle::area( void )
{ return width * length; }
void Rectangle::setWidth( double w )
{ width = w > 0 && w < 20.0 ? w : 1.0; }
void Rectangle::setLength( double l )
{ length = l > 0 && l < 20.0 ? l : 1.0;}
double Rectangle::getWidth( void ) { return width; }
double Rectangle::getLength( void ) { return length;}
OOP, Spring 2011, Engr. Anwar,
Foundation University (FUIEMS), Islamabad

2. int main()
{
Rectangle a, b( 4.0, 5.0 ), c( 67.0, 888.0 );
// output Rectangle a
cout << "a: length = " << a.getLength()<< "; width = " <<
a.getWidth()<< "; perimeter = " << a.perimeter() << "; area = " <<
a.area() << 'n';
// output Rectangle b
cout << "b: length = " << b.getLength() << "; width = " <<
b.getWidth() << "; perimeter = " << b.perimeter() << "; area = " <<
b.area() << 'n';
// output Rectangle c; bad values attempted
cout << "c: length = " << c.getLength() << "; width = " <<
c.getWidth() << "; perimeter = " << c.perimeter() << "; area = " <<
c.area() << 'n';
return 0;
}
OOP, Spring 2011, Engr. Anwar,
Foundation University (FUIEMS), Islamabad

3. Version 2:
#include <iostream>
using namespace std;
class Rectangle {
public:
Rectangle ()
{
length = 1.0;
width = 1.0;
cout<<"Constructor without parameter is called"<<endl;
}
Rectangle( double l, double w )
{
setWidth(w);
setLength(l);
cout<<"Constructor with two parameter is called"<<endl;
}
double perimeter( void )
{
return 2 * ( width + length );
}
double area( void )
{
return width * length;
}
void setWidth( double w )
{
if (w > 0 && w < 20.0)
width = w;
else
width = 1.0;
}
void setLength( double l )
{
if (l > 0 && l < 20.0)
length = l;
else
length = 1.0;
}
double getWidth( void )
{
return width;
}
double getLength( void )
{
return length;
}
OOP, Spring 2011, Engr. Anwar,
Foundation University (FUIEMS), Islamabad

4. private:
double length;
double width;
};
/*Rectangle::Rectangle( double w, double l )
{ }
double Rectangle::perimeter( void )
{}
double Rectangle::area( void )
{}
void Rectangle::setWidth( double w )
{}
void Rectangle::setLength( double l )
{}
double Rectangle::getWidth( void )
double Rectangle::getLength( void ) { }
*/
int main()
{
Rectangle a, b( 4.0, 5.0 ), c( 67.0, 888.0 );
// output Rectangle a
cout << "a: length = " << a.getLength()<< "; width = " <<
a.getWidth();
cout << "; perimeter = " << a.perimeter() << "; area = " <<
a.area() << 'n';
// output Rectangle b
cout << "b: length = " << b.getLength() << "; width = " <<
b.getWidth();
cout << "; perimeter = " << b.perimeter() << "; area = " <<
b.area() << 'n';
// output Rectangle c; bad values attempted
cout << "c: length = " << c.getLength() << "; width = " <<
c.getWidth() ;
cout << "; perimeter = " << c.perimeter() << "; area = " <<
c.area() << 'n';
return 0;
}
OOP, Spring 2011, Engr. Anwar,
Foundation University (FUIEMS), Islamabad