#include <iostream>
#include <list>

using namespace std;

class A {
public:
    void print() { cout << "Hello!" << endl; }
};

class B : public A {
public:
    void print() { cout << "Bye!" << endl; }
};

class C : public A {
public:
    void print() { cout << "Ciao!" << endl; }
};

int main() {
    list<A*> elements;
    A a;
    B b;
    C c1, c2;

    elements.push_back(&b);
    elements.push_back(&c1);
    elements.push_back(&c2);
    elements.push_back(&a);

    for (A *elem : elements) {
        elem->print();
    }

	return 0;
}

#include <iostream>
#include <list>

using namespace std;

class X {
public:
    void druck() { cout << "X"; }
};
    
class Y : public X {
public:
    void druck() { std::cout << "Y "; }
};      

class Z : public Y {};  

int main() {
    X* feld[3] = {new X, new Y, new Z};
    for (int i = 0; i < 3; ++i) {
        feld[i]->druck();
    }
    cout << endl;

    return 0;
}

#include <iostream>
#include <list>

using namespace std;

class A {
public:
    void print() { cout << "Hello!" << endl; }
};

class B : public A {
public:
    void print() { cout << "Bye!" << endl; }
};

class C : public A {
public:
    void print() { cout << "Ciao!" << endl; }
};

int main() {
    list<A*> elements;
    A a;
    B b;
    C c1, c2;

    elements.push_back(&b);
    elements.push_back(&c1);
    elements.push_back(&c2);
    elements.push_back(&a);

    for (A *elem : elements) {
        elem->print();
    }

	return 0;
}

#include <iostream>
#include <list>

using namespace std;

class A {
public:
    virtual void print() = 0;
};

class B : public A {
public:
    void print() { cout << "Bye!" << endl; }
};

class C : public A {
public:
    void print() { cout << "Ciao!" << endl; }
};

int main() {
    list<A*> elements;
    A a;
    B b;
    C c1, c2;

    elements.push_back(&b);
    elements.push_back(&c1);
    elements.push_back(&c2);
    elements.push_back(&a);

    for (A *elem : elements) {
        elem->print();
    }

	return 0;
}

#include <iostream>
#include <list>

using namespace std;

class Base {
protected:
    static int cnt;
    int id;
public:
    Base() : id(cnt++) { cout << " B(" << id << ")" << endl; }
    ~Base() { cout << "~B(" << id << ")" << endl; }
};

class Derived : public Base {
public:
    Derived() : Base() { cout << " D(" << id << ")" << endl; }
    ~Derived() { cout << "~D(" << id << ")" << endl; }
};

int Base::cnt = 1;

int main() {
    Base *b = new Derived();
    delete b;

    Derived *d = new Derived();
    delete d;

	return 0;
}