Derived classes

[Alfred]

Hi ti all!
I'd like o ask some clarification about this code.
I'd like to undestand why in main function pD->f() return D even if pE
and pD have the same value.
Do you know where I can find more information about?

Thank you very much!!!
Regards
Alfred

___________________________

#include <cstdlib>
#include <conio.h>
#include <iostream>
#include <windows.h>

using namespace std;
class B {
public:
void f() { cout << "B" << endl; };
};

class D : public B{
public: void f() { cout << "D" << endl; };
};

class E : public D {
public: void f() { cout << "E" << endl; };
};

int main()
{

E *pE = new E;
pE->f();
cout <<"pE= " << pE << endl;

D *pD = pE;
cout <<"pD= " << pD << endl;
pD->f();

system ("pause");
}

___________________________

[Zara]

On Fri, 19 Sep 2008 00:10:13 -0700 (PDT), Alfred <ga******@yahoo.com>
wrote:

>Hi ti all!
I'd like o ask some clarification about this code.
I'd like to undestand why in main function pD->f() return D even if pE
and pD have the same value.
Do you know where I can find more information about?

You must look for information about *virtual functions* and how to use
them

Best regards,

zara

[anon]

Alfred wrote:

Hi ti all!
I'd like o ask some clarification about this code.
I'd like to undestand why in main function pD->f() return D even if pE
and pD have the same value.

Because you did this:
http://www.parashift.com/c++-faq-lit....html#faq-23.8

Maybe you wanted to make the method f() virtual?

Do you know where I can find more information about?

books, online, etc

Thank you very much!!!
Regards
Alfred

___________________________

#include <conio.h>
#include <windows.h>

btw what are these two headers for??