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Doubly Linked List iterator

qtngmin (23)
Hi everyone, so today I have to deal with doubly linked list and using Iterator in it. I still don't know where i went wrong, please spend sometime help me. Thanks a lot.
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 void DLinkedList<T>::Iterator::remove() 
{
    /*
    * TODO: delete Node in pList which Node* current point to. 
    *       After that, Node* current point to the node before the node just deleted.
    *       If we remove first node of pList, Node* current point to nullptr.
    *       Then we use operator ++, Node* current will point to the head of pList.
    */
    
    Node* delN=current;
    Node*tmp=delN->next;
    current=current->previous;
    current->next=tmp;
    tmp->previous=current;
    delete[] delN;
    
    
}


Here are all the other funtions in the same class Iterator I have done, If I did it wrong, please help me figure it out.
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DLinkedList<T>::Iterator::Iterator(DLinkedList<T> *pList, bool begin) 
{
    this->pList=pList;
    if (begin == true)
    {
        if (pList != NULL) {
            index = 0;
            current = pList->head;
        }
        else {
            index = -1;
            current = NULL;
        }
    }
    else {
        current = NULL;
        if (pList != NULL) 
            index = pList->count;
        else
            index=0;
    }
}

template <class T>
typename DLinkedList<T>::Iterator& DLinkedList<T>::Iterator::operator=(const DLinkedList<T>::Iterator &iterator)
{
    this->current = iterator.current;
    this->index = iterator.index;
    this->pList = iterator.pList;
}

template <class T> 
void DLinkedList<T>::Iterator::set(const T &e)
{
    if (current == NULL)
        throw out_of_range("Segmentation fault!");
    current->data = e;
}

template<class T>
T& DLinkedList<T>::Iterator::operator*() 
{
    if (current == NULL)
        throw out_of_range("Segmentation fault!");
    else
        return current->data;
}

template<class T>
void DLinkedList<T>::Iterator::remove() 
{
    //this is the remove Iterator func 
    
    
}

template<class T>
bool DLinkedList<T>::Iterator::operator!=(const DLinkedList::Iterator &iterator) 
{
    return (this->current != iterator.current || this->index != iterator.index);
}

template<class T>
typename DLinkedList<T>::Iterator& DLinkedList<T>::Iterator::operator++() 
{
    if (current == NULL)
        throw out_of_range("Segmentation fault!");
    current=current->next;
    index++;
    return *this;
}

template<class T>
typename DLinkedList<T>::Iterator DLinkedList<T>::Iterator::operator++(int) 
{
    if (current == NULL)
        throw out_of_range("Segmentation fault!");
    Iterator tmp = *this;
    ++*this;
    return tmp;
}

mbozzi (3909)
Iterators are designed primarily to decouple algorithms from the ranges they operate upon. Algorithms like remove should not be member functions of iterator; this defeats its main purpose.
Last edited on
qtngmin (23)
I know it is already have the remove iterator but in my exercise i have to define one of this only question ( the to do one )
dhayden (5795)
It's hard to tell without seeing the declaration of DLinkedList<>, but it looks to me like remove() will fail if it deletes the first or last item. You'll access null pointers and it doesn't update the head and tail pointers.
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