class animal
{
// members, constructors and other methods...

public:
    virtual void what_do_you_eat() { cout << "i eat generic food" << endl; }
}

class cat : public animal
{
// members, constructors and other methods...

public:
    void what_do_you_eat() { cout << "i eat cat food" << endl; }
}

class dog : public animal
{
// members, constructors and other methods...

public:
    void what_do_you_eat() { cout << "i eat dog food" << endl; }
}

std::list<animal> animals
animals.push_back( dog() );
animals.push_back( cat() );

for(auto itr : animals)
{
    itr.what_do_you_eat();
}
// output:
// i eat generic food
// i eat generic food
// i eat generic food
// i eat generic food
// ...