Cpp - Inheritance Polymorphism

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Introduction

Polymorphism allows derived objects to be treated as if they were base objects.

The following code illustrates how virtual functions implement polymorphism.

Demo

#include <iostream> 
   //www  . ja va  2 s .  c  o m
class Mammal 
{ 
public: 
    Mammal():age(1) { std::cout << "Mammal constructor ...\n"; } 
    ~Mammal() { std::cout << "Mammal destructor ...\n"; } 
    void move() const { std::cout << "Mammal, move one step\n"; } 
    virtual void speak() const { std::cout << "Mammal speak!\n"; } 
   
protected: 
    int age; 
}; 
   
class Dog : public Mammal 
{ 
public: 
    Dog() { std::cout << "Dog constructor ...\n"; } 
    ~Dog() { std::cout << "Dog destructor ..\n"; } 
    void wagTail() { std::cout << "Wagging tail ...\n"; } 
    void speak() const { std::cout << "Woof!\n"; } 
    void move() const { std::cout << "Dog moves 5 steps ...\n"; } 
}; 
   
int main() 
{ 
    Mammal *pDog = new Dog; 
    pDog->move(); 
    pDog->speak(); 
    return 0; 
}

Result

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