Pointer to template class object - c++

Question

I'm trying to create a individual List with a templated value, but unfortunately I can not link from my List to the ListElements with templates.
In my main I call List<int> list1; to create a instance of the class List.
A List contains multiple ListElements that contain the value, that should be templated.
Compiler throws an error at
ListElement* first;
ListElement* last;
in List.h.
It says C2955 - 'ListElement' : use of class type requires type argument list
List.h
#pragma once
#include <string>
#include "ListElement.h"
template<class T>
class List
{
private:
ListElement* first;
ListElement* last;
public:
List();
~List();
void printList();
void pushBack(T value);
void pushFront(T value);
};
List.cpp
#include <iostream>
#include "List.h"
template<class T>
List<T>::List()
{
first = NULL;
last = NULL;
}
template<class T>
List<T>::~List()
{
}
template<class T>
void List<T>::pushBack(T value)
{
if (last)
{
ListElement* tmp = last;
last = new ListElement(value);
last->setPrev(tmp);
tmp->setNext(last);
}
else
{
first = new ListElement(value);
last = first;
}
}
template<class T>
void List<T>::pushFront(T value)
{
if (first)
{
ListElement* tmp = first;
first = new ListElement(value);
first->setNext(tmp);
tmp->setPrev(first);
}
else
{
last = new ListElement(value);
first = last;
}
}
template<class T>
void List<T>::printList()
{
if (first)
{
ListElement* tmp = first;
while (tmp)
{
std::cout << tmp->getValue() << std::endl;
if (tmp != last)
tmp = tmp->getNext();
else
break;
}
}
else
{
std::cout << "List is empty!" << std::endl;
}
}
template class List<int>;
template class List<std::string>;
ListElement.h
#pragma once
#include <string>
template<class T>
class ListElement
{
private:
ListElement* next;
ListElement* prev;
T value;
public:
ListElement(T val);
~ListElement();
ListElement* getNext() { return next; }
ListElement* getPrev() { return prev; }
void setNext(ListElement* elem) { next = elem; }
void setPrev(ListElement* elem) { prev = elem; }
T getValue() { return value; }
};
ListElement.cpp
#include "ListElement.h"
template<class T>
ListElement<T>::ListElement(T val)
{
value = val;
}
template<class T>
ListElement<T>::~ListElement()
{
}
template class ListElement<int>;
template class ListElement<std::string>;

Answer 1

ListElement is a template, so you want to use a specific instantiation for your pointers:
template<class T>
class List
{
private:
ListElement<T>* first;
ListElement<T>* last;
// note: ^^^
likewise for other occurrences. Only within the template, the template name is usable for the current instantiation, i.e., within List, you can use List as a shortcut for List<T>.