incorrect information on the polymorphism page

[Kartonagnick]

Hello!

I propose to correct the error.

on this page:
http://www.cplusplus.com/doc/tutorial/polymorphism/

snippet:

// dynamic allocation and polymorphism
#include <iostream>
using namespace std;

class Polygon {
  protected:
    int width, height;
  public:
    Polygon (int a, int b) : width(a), height(b) {}
    virtual int area (void) =0;
    void printarea()
      { cout << this->area() << '\n'; }
};

class Rectangle: public Polygon {
  public:
    Rectangle(int a,int b) : Polygon(a,b) {}
    int area()
      { return width*height; }
};

class Triangle: public Polygon {
  public:
    Triangle(int a,int b) : Polygon(a,b) {}
    int area()
      { return width*height/2; }
};

int main () {
  Polygon * ppoly1 = new Rectangle (4,5);
  Polygon * ppoly2 = new Triangle (4,5);
  ppoly1->printarea();
  ppoly2->printarea();
  delete ppoly1;
  delete ppoly2;
  return 0;
}

8.3.5 Delete
if the static type of the object to be deleted is different from its dynamic
type, the static type shall be a base class of the dynamic type of the object to be deleted and the static type
shall have a virtual destructor or the behavior is undefined.

[Ganado]

Yep, the code should have a virtual destructor.

Not sure if it'll get updated, but try the link at the bottom of the page to contact the site to report an error: http://www.cplusplus.com/contact.do?referrer=www.cplusplus.com%2Fdoc%2Ftutorial%2Fpolymorphism%2F