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Inheritance - Derive a Cylinder Class from the Circle Class
Class Declaration
// Derived Class Cylinder
class Cylinder : public Circle
{
friend double Volume(Cylinder &);
protected:
double height;
public:
Cylinder();
Cylinder(int x, int y, double r, double h);
void showdata( ostream &) const; // redefined
double area() const; // redefined
};
Class Implementation
% cat cylinder.cpp
// Cylinder class implementation - file cylinder.cpp
#include<iostream>
#include<iomanip>
using namespace std;
#include "circle.h" // header file
#include "cylinder.h"
// constructors
Cylinder::Cylinder() : Circle(), height(1.0) {} // call base class constructor
Cylinder::Cylinder(int x, int y, double r, double h)
: Circle( x, y, r) // initialization section- call base class
constructor
{
height = h;
}
void Cylinder::showdata( ostream & out ) const//
{
out << "The cylinder's base is "
<< "\n xcenter = " <<
xcenter
<< "\n ycenter = " <<
ycenter
<< "\n radius = " <<
radius << endl;
out << "cylinder height = " << height << endl;
}
double Cylinder::area() const
{
// surface area of cylinder
return 2.0*PI*radius*radius + 2.0*PI*radius*height;
}
// friend function
double Volume(Cylinder& cyl)
{
return cyl.PI * cyl.radius * cyl.radius * cyl.height;
}
Driver Function and Execution
% cat cylin.cpp
#include <iostream>
using namespace std;
#include <iomanip>
#include "circle.h"
#include "cylinder.h"
int main()
{
// declare cylinder object cx
Cylinder cx(1,1,2.0,4.0);
cx.showdata( cout );
cout << "Area = " << cx.area() << endl;
cout << "Volume = " << Volume(cx) << endl;
return 0;
}
% g++ cylin.cpp circle.cpp cylinder.cpp
% a.out
The cylinder's base is
xcenter = 1
ycenter = 1
radius = 2
cylinder height = 4
Area = 75.3982
Volume = 50.2654
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