Code getting Crashed( C++)

#include<iostream.h>
#include<memory.h>
#include<string.h>

// product
class Pizza
{
   private :
       std::string Topping;
       std::string Sauce;
       std::string Dough;

   public :
  Pizza(){}
 ~Pizza(){}

       void SetTopping(const std::string t) { Topping = t; }
       void SetSauce(const std::string s){ Sauce = s; }
       void SetDough(const std::string d){ Dough = d; }

      void ShowPizza()
 {
     std::cout <<"What a Pizza"<<std::endl
        <<"Topping is "<<Topping
        <<"Sauce is "<<Sauce
        <<"Dough is "<<Dough
        <<"! ! !"<<'\n';
 }

};

// Abstract Builder
class PizzaBuilder
{
 protected :
     std::auto_ptr<Pizza> pizza;

 public :
  PizzaBuilder(){}
  virtual ~PizzaBuilder(){}

  std::auto_ptr<Pizza> GetPizza(){return pizza;}

         virtual void BuildTopping() = 0;
         virtual void BuildSauce() = 0;
         virtual void BuildDough() = 0;

  std::auto_ptr<Pizza> CreateNew_PizzaProduct()
      { pizza.reset(new Pizza()); }

/*********** code getting crashed here ***************/

};

// concrete Pizza Builder 1
class Hawian_PizzaBuilder : public PizzaBuilder
{

    public :
 Hawian_PizzaBuilder():PizzaBuilder(){ }
 ~Hawian_PizzaBuilder(){ }
  void BuildTopping() { pizza->SetTopping(" Hawian_PizzaBuilder
Topping ");}
         void BuildSauce() { pizza->SetSauce("Hawian_PizzaBuilder
Sauce ");}
         void BuildDough() { pizza->SetDough("Hawian_PizzaBuilder
Dough ");}

};

// concrete Pizza Builder 2
class Spicy_PizzaBuilder : public PizzaBuilder
{

    public :
 Spicy_PizzaBuilder():PizzaBuilder(){}
 ~Spicy_PizzaBuilder(){}
  void BuildTopping() { pizza->SetTopping("Spicy_PizzaBuilder Topping
"); }
         void BuildSauce() { pizza->SetSauce("Spicy_PizzaBuilder
Sauce "); }
         void BuildDough() { pizza->SetDough("Spicy_PizzaBuilder
Dough "); }

};

// Director
class waiter
{
  private :
      PizzaBuilder * pizza_builder;
  public :
      waiter(): pizza_builder(NULL){}
     ~waiter(){}

     void SetPizzaBuilder(PizzaBuilder * b){ pizza_builder = b ;}
     std::auto_ptr<Pizza> GetPizza(){ return pizza_builder-


     void ConstructPizza()
      {
    pizza_builder->CreateNew_PizzaProduct();
         pizza_builder->BuildDough();
         pizza_builder->BuildSauce();
  pizza_builder->BuildTopping();
      }
};

// user
int main()
{

    waiter waiter_1;

    Spicy_PizzaBuilder spicyPizzaBuilder;
    waiter_1.SetPizzaBuilder(&spicyPizzaBuilder);

    waiter_1.ConstructPizza(); // code getting Crashed here

    std::auto_ptr<Pizza> pizza = waiter_1.GetPizza();
    pizza->ShowPizza();

return 0;
}