Use a base class' function with inherited classes values - c++

Question

Is there any way to call a parent's function from a child class but within the function use data from the child instead of the parent eg.
#include <stdio.h>
class Base{
public:
int i=10;
virtual void print(){
printf("%i", i );
}
};
class Derived : public Base {
public:
int i = 20;
void print(){
Base::print();
}
};
int main (){
Derived I;
I.print();
}
So I want this to print 20 instead of 10 basically.
EDIT ::::::::::::
What I am actually trying to do is use a base class that defines multiple functions
virtual int OnExecute();
virtual bool OnInit();
virtual void OnEvent(SDL_Event* Event);
virtual void OnLoop();
virtual void OnRender();
virtual void OnCleanUp();
Then have a derived class overload all of those functions exept OnExectue() which looks like this
if (OnInit() == 0 ){
return -1;
}
SDL_Event Event;
while (isRunning){
while (SDL_PollEvent(&Event)){
OnEvent(&Event);
}
OnLoop();
OnRender();
}
OnCleanUp();
So is there a more simplistic way where i won't be having to define 5 extra functions to pass function pointers.

Answer 1

You can do this if you provide access to the data through a virtual member function.
#include <stdio.h>
class Base{
public:
int i=10;
virtual void print(){
printf("%i", this->getI() );
}
virtual int getI()
{
return i;
}
};
class Derived : public Base {
public:
int i = 20;
void print(){
Base::print();
}
virtual int getI()
{
return i;
}
};
int main (){
Derived I;
I.print();
}

Answer 2

You need a dynamic_cast , Like this:
#include <iostream>
#include <stdio.h>
class Derived;
class Base{
public:
int i=10;
virtual void print();
};
class Derived : public Base {
public:
int i = 20;
void print(){
Base::print();
}
};
void Base::print(){
Derived* p = dynamic_cast<Derived*>(this);
if(p) {
//derived
printf("%i\n", p->i);
}else{
//base
printf("%i\n", i);
}
}
int main (){
Derived I;
I.print();
}