Answer to Question #156555 in C++ for G

Question

IN THE FORM OF OBJECT ORIENTED PROGRAMMING, C++, CREATE A PROGRAM THAT COMPUTES THE AREA OF A GIVEN RECTANGLE, AREA OF A CIRCLE AND AREA OF A TRIANGLE.

Answer 1

#include <iostream>
#include <cmath>

class Figure {
public:
    // pure virtual method
    virtual double computeArea() = 0;
};

class Rectangle : public Figure {
private:
    double w, h;
public:
    Rectangle(double width, double height) {
        w = width;
        h = height;
    }
    double computeArea() {
        return w * h;
    }
};

class Circle : public Figure {
private:
    double r;
public:
    Circle(double radius) {
        r = radius;
    }
    double computeArea() {
        return 3.141592 * r * r;
    }
};

class Triangle : public Figure {
private:
    double a, b, c;
public:
    Triangle(double A, double B, double C) {
        a = A;
        b = B;
        c = C;
    }
    double computeArea() {
        // Heron's formula
        double p = 0.5 * (a + b + c);
        double S = p * (p - a) * (p - b) * (p - c);
        return sqrt(S);
    }
};

int main() {
    Rectangle r(2, 3);
    std::cout << "Rectangle area: " << r.computeArea() << "\n";


    Circle c(2);
    std::cout << "Circle area: " << c.computeArea() << "\n";


    Triangle t(2, 3, 4);
    std::cout << "Triangle area: " << t.computeArea() << "\n";
}