template class header file - c++

Question

I'm trying to implement stack data structure using singly linked list.
This is the header file that has template class of Node and List
#pragma once
template <typename E>
class SNode {
E elem;
SNode<E>* next;
public:
friend class SLinkedList<E>;
};
template <typename E>
class SLinkedList {
private:
SNode<E>* head;
public:
SLinkedList();
~SLinkedList();
bool empty() const ();
const E& front() const;
void addFront(const E& e);
void removeFront();
};
template <typename E>
SLinkedList<E>::SLinkedList() : head(NULL) {}
template <typename E>
SLinkedList<E>::~SLinkedList() {
while(!empty()) removeFront();
}
template <typename E>
bool SLinkedList<E>::empty() const {
return head==NULL;
}
template <typename E>
const E& SLinkedList<E>::front() const {
return head->elem;
}
template <typename E>
void SLinkedList<E>::addFront(const E& e) {
SNode<E>* tmp = new SNode<E>;
tmp->elem = e;
tmp->next=head;
head=tmp;
}
template <typename E>
void SLinkedList<E>::removeFront() {
SNode<E>* old = head;
head=head->next;
delete old;
}
This is a simple main code
#include <iostream>
#include "SNode.h"
using namespace std;
int main() {
SNode<int> A(1);
SNode<int> B(2);
SLinkedList<int> L();
L.push(A);
L.push(B);
return 0;
}
When I compile this code the compiler says
SLinkedList is not a class template
I have no idea why it says that since I did put
template

Answer 1

You need to forward declare the SLinkedList templated class. like this:-
template <typename E>
class SLinkedList;
template <typename E>
class SNode {
E elem;
SNode<E>* next;
public:
friend class SLinkedList<E>;
};
...
There are other errors in you code. I hope you are able to resolve them by youself.

Answer 2

You have vexing parse with
SLinkedList<int> L();
Which declares a.. function L, taking no parameters, and returning SLinkedList<int>.
Use
SLinkedList<int> L;
or
SLinkedList<int> L{};