How do you create triangle circle and rectangle classes derived from a base class shape with virtual area function in c plus plus?

Answer 1

#include<iostream>

struct shape

{

virtual double area () const = 0;

};

struct triangle : shape

{

triangle (double b, double h): base (b), height (h) {}

double base, height;

double area () const override { return base * height / 2; }

};

struct circle : shape

{

circle (double r): radius (r) {}

double radius;

double area () const override { return 4 * atan(1) * radius * radius; }

};

struct rectangle : shape

{

rectangle (double w, double h): width (w), height (h) {}

double width, height;

double area () const override { return width * height; }

};

int main()

{

triangle t (10, 5);

std::cout << "triangle with base " << t.base << " and height " << t.height << " has area " << t.area() << std::endl;

circle c (5);

std::cout << "circle with radius " << c.radius << " has area " << c.area() << std::endl;

rectangle r (10, 5);

std::cout << "rectangle with width " << r.width << " and height " << r.height << " has area " << r.area() << std::endl;

}