Problem with Template Classes

[kevinkjt2000]

My code looks like this:

template <typename T, typename R>
class LinkedList{
private:
	class Node{
	public:
		R data;
		Node* next;
		Node(const R& el): data(el), next(NULL){}
	}; // end Node class definition
	
	int size;
	Node* first;
	Node* findptr(const T&);
public:
	LinkedList();
	~LinkedList();
	void insert(const R&);
	bool find(const T&, R&);
	bool erase(const T&);
	void display();
}; // end LinkedList class definition

template <typename T, typename R>
LinkedList<T, R>::Node* LinkedList<T, R>::findptr(const T& key){
	Node* ptr = first;
	while(ptr!=NULL){
		if (ptr->data == key)
			return ptr;
		ptr = ptr->next;
	}
	return NULL;
}

The problem is with LinkedList<T, R>::Node*. For some reason the compiler really doesnt like the "*", but I have used code like this before just without templates and it worked just fine. Help?

Error: expected constructor, destructor, or type conversion b
efore '*' token
Error: expected `;' before '*' token

[guestgulkan]

You need to make use of the keyword typename to clarify that LinkedList<T, R>::Node is a type.
See here:
http://books.google.co.uk/books?id=EotSAwuBkJoC&pg=PA43&lpg=PA43&dq=c%2B%2B+templates+keyword+typename&source=bl&ots=iwNYG8-i9b&sig=daCPb4AXAz_3FklfI8VMnM2Nt8k&hl=en&ei=73bHS5LIOJv80wTd09TNDA&sa=X&oi=book_result&ct=result&resnum=10&ved=0CCEQ6AEwCQ#v=onepage&q=c%2B%2B%20templates%20keyword%20typename&f=false

[kevinkjt2000]

Thanks I have been looking around for a while now. After reading some of that book you found, I don't think I will ever use templates again. They just seem so confusing now.

Edit: Okay after reading that chapter, I still can't figure out how to fix my code and get rid of that error. I changed my code back to how it was originally and also I would like to note that the non-template version of this works fine for some reason:

typedef std::string KeyType; // makes KeyType a synonym for std::string

struct Article{
string title, author; 
KeyType key;
};

typedef struct Article ElementType; // makes ElementType a synonym for struct Article

class LinkedList{
private:
	class Node{
	public:
		ElementType data;
		Node* next;
		Node(const ElementType &el): data(el), next(NULL){}
	}; // end Node class definition
	
	int size;
	Node* first;
	Node* findptr(const KeyType &key);
public:
	LinkedList();
	~LinkedList();
	void insert(const ElementType&);
	bool find(const KeyType&, ElementType&);
	bool erase(const KeyType&);
	void display();
}; // end LinkedList class definition

LinkedList::Node* LinkedList::findptr(const KeyType &key){
	Node* ptr = first;
	while(ptr!=NULL){
		if (ptr->data == key)
			return ptr;
		ptr = ptr->next;
	}
	return NULL;
}

I can't see why the template one would not work... ::bangsheadonwall::

Edit #2: I decided to just ditch the templates for this program, but it would be beneficial if anyone can tell me what is wrong for future reference. Thanks in advance.

[jsmith]

As was pointed out:

// note the "typename"
template <typename T, typename R>
typename LinkedList<T, R>::Node* LinkedList<T, R>::findptr(const T& key){
	Node* ptr = first;
	while(ptr!=NULL){
		if (ptr->data == key)
			return ptr;
		ptr = ptr->next;
	}
	return NULL;
}