simple program using abstract classes and pure virtual function (OOP) (74)

#include<iostream>

using namespace std;

class shape

{

protected:

string colour;

public:

void input(string x) //simple member function

{

colour=x;

cout<<"colour is:"<<colour<<endl;

}

virtual double area()=0; //pure virtual function

};

class rectangle:public shape //inherit with shape class

{

private:

int length,width;

public:

void rectan(int x,int y)

{

length=x;

width=y;

}

double area() //define the pure virtual function

{

return width*length;

}

};

class triangle:public shape    //define the pure virtual function

{

int base,height;

public:

void tring(int x,int y)

{

base=x;

height=y;

}

double area()

{

return base*height/2;

}

};

int main()

{

shape *obj1; //making the pointer of base class shape

rectangle obj2; //making the object of rectangle class

obj1=&obj2;//pointer of shape class take the object of rectangle class

obj2.rectan(3,4);

obj1->area();

obj2.input("green");

cout<<"the area of the rectangle is:"<<obj1->area()<<endl;

triangle obj3;//making the object of triangle class

obj1=&obj3;//pointer of shape class take the object of triangle class

obj3.tring(4,8);

obj1->area();

cout<<"the area of the triangle is:"<<obj1->area()<<endl;

}