Template in C++

I am trying to implement a singly linked list that stores multiple types of item. So I came across templates, but when I tried running the following code, the compiler gives me several linking errors (LNK 2019: unresolved external symbol). I haven't really done anything yet and can't figure out what went wrong. Can anyone please point out my mistake??

singlylinkedlist.h

template 
class SinglyLinkedList
{
public:
    SinglyLinkedList();
    ~SinglyLinkedList();

private:

    template 
    struct Node {
        I item;
        Node *next;
    };

    Node *head; 
};

singlylinkedlist.cpp

#include "singlylinkedlist.h"

template 

SinglyLinkedList::SinglyLinkedList()
{
    head = NULL;
}

main.cpp

#include 
#include "singlylinkedlist.h"

using namespace std;

int main()
{
    SinglyLinkedList list;

}

Answer

There are a number of small issues with the code, for example, you haven't implemented the destructor, and you don't really need to templatize Node. Change your implementation as follows,

// singlylinkedlist.h
template 
class SinglyLinkedList
{
public:

    SinglyLinkedList() : head(NULL) {}
    ~SinglyLinkedList() {}

private:
    struct Node {
        Item item;
        Node *next;
    };
    Node *head; 
};


// main.cpp
#include "singlylinkedlist.h"
using namespace std;

int main()
{
    SinglyLinkedList list;
}