question about polymorphism in c++

[tpopono]

Hello, im starting out in c++ and i want to know why this code prints out base

struct base 
{
    virtual void foo(void){
        cout<<"base"<<endl;
    }
 }
 struct derived : base(void)
 {
   void foo(void){
       cout<<"derived"<<endl;
   }
 }
 
int main (void)
 {
 base *b = new derived;
 b -> foo();
 return 0
 }

i know that when making a program like this in java the output would be derived.. I would like to know how it works in c++. thank you for your time

[Paul McKenzie]

Hello, im starting out in c++ and i want to know why this code prints out base

That code doesn't even compile. Next time, post real code. We have no idea why you get output with a program that is not the one you posted.

#include <iostream>
using namespace std;

struct base 
{
    virtual void foo(void){
        cout<<"base"<<endl;
    }
};

struct derived : base
{
   void foo(void){
       cout<<"derived"<<endl;
    }
};

int main ()
{
     base *b = new derived;
     b -> foo();
     return 0;
}

The following prints out "derived". However, there is a problem with it in that

1) The code has a memory leak (Java is not C++ -- the usage of new in Java is not the same as in C++). Please do not use Java as a model in learning C++ as it just leads to confusion, both in learning the proper C++ fundamentals and in writing C++ code.

2) The base class should have a virtual destructor, since you are using base class pointers, dynamically allocated memory, and accessing virtual functions through the base class pointer.

Regards,

Paul McKenzie