Writing an Iterator for a Custom Class - c++

Question

I'll preface this by saying I am mostly working off of examples written by others, so my understanding of template classes and friend classes is subpar. I am trying to write a circular list class:
#ifndef CIRCLIST_H
#define CIRCLIST_H
#include <cstdlib>
#include <iostream>
using namespace std;
template <class T>
class Node
{
public:
Node() : next(NULL), prev(NULL) {}
Node(const T& v) : value(v), next(NULL), prev(NULL) {}
T value;
Node<T>* next;
Node<T>* prev;
};
template <class T> class circList; //Forward declaration
template <class T>
class circIterator
{
public:
circIterator() : ptr(NULL) {}
~circIterator() {}
T& operator*() { return ptr->value; }
circIterator<T> & operator=(const circIterator<T> & old) { ptr = old.ptr; return *this; }
circIterator<T> & operator++() { ptr = ptr->next; return *this; }
circIterator<T> & operator--() { ptr = ptr->prev; return *this; }
friend class circList<T>;
friend bool operator==(const circIterator<T>& l, const circIterator<T>& r) { return l.ptr == r.ptr; }
friend bool operator!=(const circIterator<T>& l, const circIterator<T>& r) { return l.ptr != r.ptr; }
private:
Node<T>* ptr;
};
template <class T>
class circList
{
//class circIterator;
public:
circList() : entry(NULL), vsize(0) {}
~circList() {}
unsigned int size() const {return size;}
typename circList<T>::template circIterator<T> add(T const& v, circIterator<T> itr);
private:
Node<T>* entry;
unsigned int vsize;
};
template <class T>
typename circList<T>::template circIterator<T> circList<T>::add(T const& v, circIterator<T> itr)
{...}
When I write a simple main.cpp which simply declares a circList, I get the error:
error: no class template named 'circIterator' in 'class circList<int>'
The error references the last line, where the add function is implemented. What exactly does this mean? Does it mean that somewhere I have to code how an circIterator should "belong" to an circList? I really have no idea.

Answer 1

The error is caused by the fact that in circList<T>::template you are trying to access an identifier template (which is a keyword) that is not set for the class.
Just define the function as:
template <class T>
circIterator<T> circList<T>::add(T const& v, circIterator<T> itr) {...}
and declare it as:
circIterator<T> add(T const& v, circIterator<T> itr);
And here is the working example.