Abstract classes by virtual function with no body
#include <iostream> using namespace std; class Animal{ public: Animal(int health = 100); virtual void Greet() const = 0; //pure virtual member function virtual void DisplayHealth() const; protected: int m_Health; }; Animal::Animal(int health): m_Health(health){} void Animal::DisplayHealth() const{ cout << "Health: " << m_Health << endl; } class Orc : public Animal{ public: Orc(int health = 120); virtual void Greet() const; }; Orc::Orc(int health): Animal(health) {} void Orc::Greet() const { cout << "The orc grunts hello.\n"; } int main() { Animal* pAnimal = new Orc(); pAnimal->Greet(); pAnimal->DisplayHealth(); return 0; }