An example of dynamic_cast

Lets look at an example of dynamic_cast where you can cast a pointer from Derived class to Base class. The example should be self explanatory:

//Program tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
//A very simple program to explain dynamic cast

#include <iostream>

using namespace std;

//Base class
class A
{
public:
  int a;
  int b;
private:
  int c;
};

//Derived class
class B :public A
{
private:
  int d;
};

//function that prints a and b
void function(A a)
{
  cout<<"\n a = "<<a.a<<"      b = "<<a.b<<endl;
}

int main()
{
  A *a;
  B *b=new(B);
  b->a = 20, b->b = 40;
  a = dynamic_cast<A*>(b); //Dynamic cast from Dervied to Base
  function(*a);
  return 0;
}

The output is as follows: