I know there must be lots of these posted, but I search on google and on here, and I'm still having trouble.

We still haven't covered iterators fully and I'm having trouble with it. If anyone has a link to how iterators work (w/anything) that includes code, please let me know.

Anyway, I have a linked list class and an iterator class. I'll just try to post the relevant code.

One of the errors that I get is a warning that a reference to local variable 'it' is returned. I think I understand the error, but I'm not sure how to solve it. Any help is appreciated. Thanks.

**********LINKEDLIST CLASS AND MAIN***********

// LinkedList and main are together. they're not separate files.

Code:#include <iostream> #include <conio.h> using namespace std; template <class T> class Node { public: T data; Node<T>* next; Node<T>* prev; Node(){ next = NULL; prev = NULL;} }; #include "ListIterator.h" template <class T> class LL { public: LL(); ListIterator<T> &begin(); ListIterator<T> &end(); private: Node<T>* head; friend class ListIterator<T>; }; template <class T> ListIterator<T>& LL<T>::begin() { ListIterator<T> it(head); return it; } template <class T> ListIterator<T>& LL<T>::end() { // This is wrong... I'm not sure how to do this... ListIterator<T> it(head); while(it.hasNext()) return it; } int main() { LL<int> obj; obj.pushFront(3); obj.pushFront(4); //obj.printList(cout); ListIterator<int> iter = obj.begin(); getch(); return 0; }

*********LISTITERATOR CLASS*************

Code:using namespace std; template <class T> class ListIterator { public: Node<T> *current; ListIterator() {} ListIterator(Node<T>*); bool hasNext(); bool hasPrevious(); T next(); T previous(); void insert(T val); void remove(); }; // template <class T> ListIterator<T>::ListIterator(Node<T> *head) { current = head; } // Returns true if it has a next node template <class T> bool ListIterator<T>::hasNext() { return (current->next == NULL); } // Returns true if it has a previous node template <class T> bool ListIterator<T>::hasPrevious() { return (current->previous == NULL); } // Returns next node's data template <class T> T ListIterator<T>::next() { if(!this->hasNext()) return; return (current->next->data); } // Returns previous node's data template <class T> T ListIterator<T>::previous() { if(!this->hasPrevious()) return; return (current->prevous->data); } template <class T> void ListIterator<T>::insert(T val) { Node<T> newNode = new Node<T>(val); if(this->hasNext()) { newNode->back = current; newNode->next = current->next; current->next->back = newNode; current->next = newNode; } // Last one in list else if(this->hasPrevious()) { newNode->back = current; current->next = newNode; } } // Remove function template <class T> void ListIterator<T>::remove() { if(current == NULL) return; current->next->back = current->back; current->back->next = current->next; delete current; }