c++virtual method

c++

/*
 * =====================================================================================
 *
 *       Filename:  test.cpp
 *
 *    Description:  G
 *
 *        Version:  1.0
 *        Created:  12/29/2012 08:50:05 AM
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  freetstar (http://www.freetstar.com), [email protected]
 *        Company:  
 *
 * =====================================================================================
 */
#include <iostream>
using namespace std;

class A
{
    public:
        virtual void foo(){cout<<"A::foo() is called"<<endl;}
};

class B: public A
{
    public:
        virtual void foo(){cout<<"B:foo() is called"<<endl;}
};

int main(int argc, const char *argv[])
{
    A * a = new B();
    a->foo();
    return 0;
}