Virtual functions

virt.cpp

#include <iostream>
using namespace std;

class Animal {
    string latin_name;
public:
    Animal(string latin_name) : latin_name{latin_name} {}
    virtual ~Animal() { cerr << "Animal::~Animal called for " << latin_name << endl; }
    virtual string get_display_name() const { return latin_name; }
    virtual int foo() = 0;
    friend ostream& operator<<(ostream &os, const Animal &a);
};
class Pet : public Animal {
    string name;
public:
    Pet(string name, string latin_name) : Animal{latin_name}, name{name} {}
    ~Pet() { cerr << "Pet::~Pet called for " << name << endl; }
    int foo() override { return 42; }
    string get_display_name() const override
    { return name + '(' + Animal::get_display_name() + ')'; }
};
ostream& operator<<(ostream &os, const Animal &a)
{ return os << a.get_display_name(); }

int main() {
    Animal *kitty = new Pet("Mimi", "felis catus");
    Animal *doggy = new Animal("canis familiaris");
    Animal &a = *kitty;
    cout << a << endl << *doggy << endl;
    delete kitty;
    delete doggy;
    return 0;
}