A simple example using a virtual function.


#include <iostream>
using namespace std;

class BaseClass {
public:
  int i;
  BaseClass(int x) { 
     i = x; 
  }
  virtual void myFunction()
  {
    cout << "Using BaseClass version of myFunction(): ";
    cout << i << '\n';
  }
};

class DerivedClass1 : public BaseClass {
public:
  DerivedClass1(int x) : BaseClass(x) {}
  void myFunction() 
  {
    cout << "Using DerivedClass1's version of myFunction(): ";
    cout << i*i << '\n';
  }
};

class DerivedClass2 : public BaseClass {
public:
  DerivedClass2(int x) : BaseClass(x) {}
  void myFunction() 
  {
    cout << "Using DerivedClass2's version of myFunction(): ";
    cout << i+i << '\n';
  }
};

int main()
{
  BaseClass *p;
  BaseClass ob(10);  
  DerivedClass1 derivedObject1(10);   
  DerivedClass2 derivedObject2(10); 

  p = &ob;
  p->myFunction();                         // use BaseClass's myFunction()

  p = &derivedObject1;
  p->myFunction();                         // use DerivedClass1's myFunction()

  p = &derivedObject2;
  p->myFunction();                         // use DerivedClass2's myFunction()

  return 0;
}

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2.	Virtual function: respond to random events
3.	Use virtual function to define interface.
4.	Virtual functions retain virtual nature when inherited.
5.	Virtual function and public inheritance
6.	Virtual function and three level inheritance
7.	Virtual function for two derived classes
8.	Class pointer and virtual function

A simple example using a virtual function. : Virtual « Function « C++

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