Thread: Container - Iterator ++it

Hello

I am trying to create a container. But I have a problem with my iterator.
I can print everything out using a for statement it->getNext(). So I know my container/iterator works.

But when I am using ++it I get a segfault. (bold)
I know my operator++ is wrong but I dont know how to make it work.

Can someone help me?

Thank you

Code:

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

class Artikel{

  public:
  Artikel(){}
    Artikel(string m_naam, float m_prijs)
      :naam(m_naam), prijs(m_prijs){}

    Artikel(const Artikel &other)
    {
      naam = other.naam;
      prijs = other.prijs;
    }

    string getNaam()
    {
      return naam;
    }

    float getPrijs()
    {
      return prijs;
    }


    friend ostream& operator<<(ostream &out, const Artikel &k)
    {
     out << k.naam << " " << k.prijs << endl;
      return out;
    }
  private:
    string naam;
    float prijs;

};

class Iterator{

  public:
    Iterator(Artikel *m_current = NULL, Iterator *m_next = NULL){
      next = m_next;
      if(m_current != NULL)
	current = new Artikel(*m_current);
      else
	current = NULL;
    }

    Iterator(const Iterator&other)
    {
      cout << "copy iterator\n";
      current = new Artikel(*other.current);
      next = other.next;

    }

    Iterator* getNext()
    {
      return next;
    }

    Artikel& getArtikel()
    {
      return *current;
    }

    void setNext(Iterator *it)
    {
      next = it;
    }

    bool operator!=(const Iterator& other)
    {
      if(current == other.current)
        return false;
      else
        return true;
    }

    friend ostream& operator<<(ostream &out, const Iterator&k)
    {
      out << k.current->getNaam() << k.current->getPrijs() << endl;
      return out;
    }

    Iterator& operator++()
    {
      *this = *next;
      this->current = next->current;
      return *this;
    }



  private:
    Iterator *next;
    Artikel *current;

};

class Container{

  public:

    Iterator* getTail()
    {
      return tail;
    }

    Iterator* getHead(){
      return head;
    }
    void Add(Artikel *a);
    Container(){
      head = NULL;
      tail = new Iterator();
    }
  private:

    Iterator *tail, *head;


};

void Container::Add(Artikel *a)
{

  if(head == NULL)
  {
    head = new Iterator(a, tail);
  } else {

    Iterator *it = head;

    while(it->getNext() != tail)
    {
        it = it->getNext();
    }

    Iterator *add = new Iterator(a, tail);
    it->setNext(add);


  }


}



int main(void){

  Artikel a1("Karskall ", 12.45);
  Artikel a2("Alfa-beta ", 1.12);
  Artikel a3("dijkstra ", 45.23);
  Artikel a4("Floyd ", 1003.34);

  Container c;

  c.Add(&a1);
  c.Add(&a2);
  c.Add(&a3);
  c.Add(&a4);

  Iterator *it;
/* WORKS
  for(it = c.getHead(); it != c.getTail(); it = it->getNext())
  {
    cout << *it;
  }
*/
  for(it = c.getHead(); it != c.getTail(); ++it)
  {
    cout << *it;
  }


  return 0;
}

"this" isn't really a modifiable kind of thing. Presumably you want to change "current" instead.