CODEWITHSUNDEEP
c++templates
Shikhar Nigam
Shikhar Nigam

Reputation: 73

C++ Template, learning for the first time, what is wrong with this code?

I am learning C++ templates for the first time, and have copied this code from "Data Structures and Algorithms in C++ by Michael Goodrich."

I get the error "Line 13: SLinkedList is not a template." I am at a complete loss as to why it is not since I have used "template " everywhere.

    // ------------------ DEFINITION FOR NODE ------------------------
template <typename E>
class SNode{

    private:
        E elem;
        SNode<E>* next;


        friend class SLinkedList<E>;

    public:
        SNode(E element = NULL);
        const E getElem() const;
        void setElem(E element);


};

template <typename E>
SNode<E>::SNode(E element){ elem = element;}

template <typename E>
const E SNode<E>::getElem() const
    {return elem;}

template <typename E>
void SNode<E>::setElem(E element)
    {elem = element;}






// -------------------- DEFINITION FOR SINGLY-LINKED LIST --------------
template <typename E>
class SLinkedList
{
    private:
        SNode<E>* head;

    public:
        SLinkedList();
        ~SLinkedList();
        bool isempty() const;
        const E& infront() const;
        void addfront(const E& e);
        void removefront();


};

template <typename E>
SLinkedList<E>::SLinkedList()
    :head(NULL) {}

template <typename E>
SLinkedList<E>::~SLinkedList()
    {while(!isempty()) removefront();}

template <typename E>
bool SLinkedList<E>::isempty() const
    {return (head == NULL);}

template <typename E>
const E& SLinkedList<E>::infront() const {return head->elem;}

template <typename E>
void SLinkedList<E>::addfront(const E& element) {

    SNode<E>* v = new SNode<E>;
    v->elem = element;
    v->next = head;
    head = v;
}

template <typename E>
void SLinkedList<E>::removefront() {
    SNode<E>* old = head;
    head = old->next;
    delete old;

}

int main()
{


    std::cout<<"Checking SLinkedList ..."<<std::endl<<std::endl;


    SLinkedList<int> intList;
    intList.addfront(13);
    std::cout<<intList.head->next->getElem();


    return 0;
}

Upvotes: 1

Views: 188

Answers (2)

Kornel Kisielewicz
Kornel Kisielewicz

Reputation: 57545

friend class SLinkedList<E>;

This can be anything. The compiler doesn't know what it is. But if you tell him before declaring SNode that it will be defined later...:

template <typename E>
class SLinkedList;

... it might work ;)

Upvotes: 2

Saksham
Saksham

Reputation: 9380

You are using SLinkedList<E> even before declaring it. Before using it in you class `SNode', please declare it which is known as forward declaration.

Upvotes: 2

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