// File: ex7-15.cpp - Abstract classes

#include <iostream>
#include <cmath>
#include <cstdlib>
using namespace std;

const double pi = 3.141592654;

class Shape
{
protected:
    double x;
    double y;
public:
    Shape(double = 0,double = 0);
    double get_x() const
    {
        return x;
    }
    double get_y() const
    {
        return y;
    }
    virtual double area() const = 0;	// pure virtual function

    virtual double girth() const = 0;	// pure virtual function

};

Shape::Shape(double c_x, double c_y) : x(c_x),y(c_y) {}

ostream& operator<<(ostream& out, const Shape& object)
{
    cout << '(' << object.get_x() << ',' << object.get_y() << ')';
    return out;
}

class Square : public Shape
{
private:
    double side;
public:
    Square(double c_x,double c_y, double s);
    double get_side()
    {
        return side;
    }
    double area() const;
    double girth() const;
};

Square::Square(double c_x, double c_y, double s) : Shape(c_x,c_y), side(s)
{ }

double Square::area() const
{
    return side * side;
}

double Square::girth() const
{
    return 4.*side;
}

class Triangle : public Shape
{
private:
    double a,b,c;	// length of 3 sides

public:
    Triangle(double c_x,double c_y, double s1, double s2, double s3);
    void print_sides();
    double area() const;
    double girth() const;
};

Triangle::Triangle(double c_x, double c_y, double s1, double s2, double s3)
    : Shape(c_x,c_y), a(s1), b(s2), c(s3)
{ }

void Triangle::print_sides()
{
    cout << a << ' ' << b << ' ' << c;
}

double Triangle::area() const
{
    double s = (a + b + c) / 2.;	// semiperimeter

    return sqrt(s*(s-a)*(s-b)*(s-c));
}

double Triangle::girth() const
{
    return a+b+c;
}

class Circle : public Shape
{
private:
    double radius;
public:
    Circle(double c_x, double c_y, double r);
    double get_radius()
    {
        return radius;
    }
    double area() const;
    double girth() const;
};

Circle::Circle(double c_x, double c_y, double r) : Shape(c_x,c_y), radius(r)
{ }

double Circle::area() const
{
    return pi*radius*radius;
}

double Circle::girth() const
{
    return 2.*pi*radius;
}

int main()
{
    //  Shape sh(6,7);	can't create instance of abstract class

    Circle c(3,4,5);
    cout << "Circle c - center: ";
    cout << c << endl;
    cout << "  radius = " << c.get_radius();
    cout << "  area = " << c.area();
    cout << "  circumference = " << c.girth() << endl;

    Square s(5.,2.,1.);
    cout << "Square s - center: ";
    cout << s << endl;
    cout << "  side = " << s.get_side();
    cout << "  area = " << s.area();
    cout << "  perimeter = " << s.girth() << endl;

    Triangle t(0,0,3,4,5);
    cout << "Triangle t - center: ";
    cout << t << endl;
    cout << "  sides = ";
    t.print_sides();
    cout << "  area = " << t.area();
    cout << "  perimeter = " << t.girth() << endl;

    cout << "sizeof(double)=" << sizeof(double) << endl;
    cout << "sizeof(Shape)=" << sizeof(Shape) << endl;
    cout << "sizeof(Square)=" << sizeof(Square) << endl;
    cout << "sizeof(Triangle)=" << sizeof(Triangle) << endl;
    cout << "sizeof(Circle)=" << sizeof(Circle) << endl;
}