Pure Virtual functions and RTTI

This is the most basic question I ever have. Here is the code that when I run on my VC++ VS6.0 SP6, gives me the output given just below that code.

//CODE

#include <iostream>
#include <typeinfo>
using namespace std;


class Shape
{
public:
      Shape()
      {
            cout<<"Constructing Shape"<<endl;
      }
      ~Shape()
      {
            cout<<"Destroying Shape"<<endl;
      }
      virtual void draw() = 0;
};

class Line : public Shape
{
public:
      Line()
      {
            cout<<"Constructing Line"<<endl;
      }
      ~Line()
      {
            cout<<"Destroying Line"<<endl;
      }
      void draw()
      {
            cout << "**********"<<endl;
      }
};

class Rectangle : public Shape
{
public:
      Rectangle()
      {
            cout<<"Constructing Rectangle"<<endl;
      }
      ~Rectangle()
      {
            cout<<"Destroying Rectangle"<<endl;
      }
      void draw()
      {
            cout << "**********\n*        *\n*         *\n**********"<<endl;
      }
};

class Triangle : public Shape
{
public:
      Triangle()
      {
            cout<<"Constructing Triangle"<<endl;
      }
      ~Triangle()
      {
            cout<<"Destroying Triangle"<<endl;
      }
      void draw()
      {
            cout << "*\n* *\n*****"<<endl;
      }
};

class NullShape : public Shape
{
public:
      NullShape()
      {
            cout<<"Constructing NullShape"<<endl;
      }
      ~NullShape()
      {
            cout<<"Destroying NullShape"<<endl;
      }
      void draw()
      {
      }
};

Shape *generate()
{
      switch(rand() % 4)
      {
            case 0:
                  return new NullShape;
            case 1:
                  return new Line;
            case 2:
                  return new Triangle;
            case 3:
                  return new Rectangle;
      }
      return NULL;
}

int main()
{
      int i;
      Shape *shapePtr;
      

      for (i=0;i<10;i++)
      {
            shapePtr = generate();
            //cout << typeid(*shapePtr).name();
            shapePtr->draw();
            if (shapePtr  != NULL)
                  delete shapePtr;
            cout<<endl<<endl;
      }

      return 0;
}

//OUTPUT I GOT

Constructing Shape
Constructing Line
**********
Destroying Shape


Constructing Shape
Constructing Rectangle
**********
*        *
*         *
**********
Destroying Shape


Constructing Shape
Constructing Triangle
*
* *
*****
Destroying Shape


Constructing Shape
Constructing NullShape
Destroying Shape


Constructing Shape
Constructing Line
**********
Destroying Shape


Constructing Shape
Constructing NullShape
Destroying Shape


Constructing Shape
Constructing Triangle
*
* *
*****
Destroying Shape


Constructing Shape
Constructing Triangle
*
* *
*****
Destroying Shape


Constructing Shape
Constructing Triangle
*
* *
*****
Destroying Shape


Constructing Shape
Constructing NullShape
Destroying Shape
-------------------------------------------------

When each time an object of type derived is destroyed, that is pointed to by a base class pointer, I can see from the outut that only base class destructor is called. However, I guess it should be the corresponding derived class destructor becuase the actual object being destructed is of devied type. Why this is so Please explain.

Another thing if I remove comment statement in for loop in main function:

//cout << typeid(*shapePtr).name();

It does not gives me any names of the type of objects being pointed by the base class pointer as I guess it should be. However, it gives me a warning and a run time error:

Warning:

warning C4541: 'typeid' used on polymorphic type 'class Shape' with /GR-; unpredictable behavior may result

Run time Error:

Abnormal Program Termination (Retry, Debug, Teminate)

Please help.