#include <iostream>
const float pi = 3.14159;
class Figura
{
public:
virtual float pole() const
{
return -1.0;
}
};
class Kwadrat : public Figura
{
public:
Kwadrat( const float bok ) : a( bok ) {}
float pole() const
{
return a * a;
}
private:
float a; // bok kwadratu
};
class Kolo : public Figura
{
public:
Kolo( const float promien ) : r( promien ) {}
float pole() const
{
return pi * r * r;
}
private:
float r; // promien kola
};
void wyswietlPole( Figura &figura )
{
std::cout << figura.pole() << std::endl;
return;
}
int main()
{
// deklaracje obiektow:
Figura jakasFigura;
Kwadrat jakisKwadrat( 5 );
Kolo jakiesKolo( 3 );
Figura *wskJakasFigura = 0; // deklaracja wskaźnika
// obiekty -------------------------------
std::cout << jakasFigura.pole() << std::endl; // wynik: -1
std::cout << jakisKwadrat.pole() << std::endl; // wynik: 25
std::cout << jakiesKolo.pole() << std::endl; // wynik: 28.274...
// wskazniki -----------------------------
wskJakasFigura = &jakasFigura;
std::cout << wskJakasFigura->pole() << std::endl; // wynik: -1
wskJakasFigura = &jakisKwadrat;
std::cout << wskJakasFigura->pole() << std::endl; // wynik: 25
wskJakasFigura = &jakiesKolo;
std::cout << wskJakasFigura->pole() << std::endl; // wynik: 28.274...
// referencje -----------------------------
wyswietlPole( jakasFigura ); // wynik: -1
wyswietlPole( jakisKwadrat ); // wynik: 25
wyswietlPole( jakiesKolo ); // wynik: 28.274...
return 0;
}
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