Re: Is it legal code?

From:
"Paul" <pchristor@yahoo.co.uk>
Newsgroups:
comp.lang.c++
Date:
Tue, 1 Mar 2011 18:41:51 -0000
Message-ID:
<T5bbp.76147$P95.25470@newsfe05.ams2>
"Gerhard Fiedler" <gelists@gmail.com> wrote in message
news:7l4qxi2mntr9.dlg@gelists.gmail.com...

Paul wrote:

I think this proves the same point using standard C++ code:

#include <iostream>
class Animal{public:
virtual void eat(){std::cout<< "Animal Eating"<< std::endl;}
virtual int getID()=0;
static int count;
};
class Dog: public Animal{
public:
void eat(){std::cout<< "Dog Eating"<< std::endl;}
int getID(){return 1;}
};
class Cat: public Animal{
public:
void eat(){std::cout<< "Cat Eating"<< std::endl;}
int getID(){return 0;}
};
int Animal::count =10;

Dog* overwriteCat(Animal* ptr){
 delete ptr;
 Dog* p = reinterpret_cast<Dog*>(ptr);
 p = new Dog;
 return p;
}

Cat* overwriteDog(Animal* ptr){
 delete ptr;
 Cat* p = reinterpret_cast<Cat*>(ptr);
 p = new Cat;
 return p;
}

void ordinary_function(Animal* obj){
 Animal::count--;
 std::cout<<"Address of obj: " <<obj << " ";
 obj->eat();
 if(obj->getID()){overwriteDog(obj);}
 else {overwriteCat(obj);}
 if(Animal::count){
  ordinary_function(obj);
 }
}

int main()
{
 Cat* p_cat = new Cat;
 Animal* p_anim = p_cat;

 ordinary_function(p_cat);
}


What point are you trying to prove with this code?


It proves a function can be recursed with a different object parameter each
recursion.

This cannot be done with a NSMF, thus it proves a significant difference
between an ordinary function an a NSMF.

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