Typename AND Class in one template?

[packetpirate]

I've been working on a Linked List class in a header file and I'm confused as to how I should proceed with this... so far, I can create a list of a data type, such as int, double, or float, but I can't figure out how I could change the template so that it could accept both data types and objects of classes. I could change the template to template< class T >, but then it gives me a syntax error when I try to create a list of INTs or other data types. What can I do? Here's my code:

/**
* This header file was designed to make creation and modification of linked lists easier.
* Author - packetpirate
* Last Update - 05/18/2011  11:19 PM
**/

#ifndef LINKEDLIST_H
#define LINKEDLIST_H

#include <iostream>
using std::cout;
using std::endl;

// Begin linklist namespace.
namespace linklist
{
	// Begin node structure.
	template< typename T >
	struct node {
		T data; // Contains data of specified type.
		node<T> *link; // Contains link to next node. NULL if this node is last in the list.
	};
	// End node structure.

	// Begin LinkedList class declaration.
	template< typename T >
	class LinkedList {
		public:
			LinkedList(); // Creates a new blank list.
			LinkedList(node<T> *start); // Creates a new list with a specified first node.
			~LinkedList();

			// Functions for appending the list.
			void add(node<T> *next); // Adds a node to the list.
			void add(T nextData); // Adds a new node to the list.

			// Get and Set functions for the list.
			T get(int pos);
			void set(int pos, T newData);

			// Size-based functions.
			int length();
			bool isEmpty();

			// Position-based functions.
			T begin(); // Returns the data of the first node in the list.
			T end(); // Returns the data of the last node in the list.

			// Sort function/s.
			void sort(bool asc);
			void swap(node<T> *i, node<T> *j);

			// Print functions.
			void printList();
			void printElem(int pos);
		private:
			node<T> *first; // The first node in the list.
			node<T> *last; // The last node in the list.
			int size; // Size of the list.
	};
	// End LinkedList class declaration.

	// Begin LinkedList class definitions.
	// Begin Constructors & Destructors
	template< typename T >
	LinkedList<T>::LinkedList() {
		first = NULL;
		last = NULL;
		size = 0;
	}
	template< typename T >
	LinkedList<T>::LinkedList(node<T> *start) {
		if(start->link != NULL) {
			first = start;
			node<T> *current = start;
			int count = 0;

			for(current = start;current != NULL;current = current->link) {
				count++;
				if(current->link == NULL) {
					last = current;
					size = count;
				}
			}
		} else {
			first = start;
			last = start;
			size = 1;
		}
	}
	template< typename T >
	LinkedList<T>::~LinkedList() {

	}
	// End Constructors & Destructors

	// Begin list modifying functions.
	template< typename T >
	void LinkedList<T>::add(node<T> *next) {
		if(first == NULL) {
			first = next;
			last = next;
			last->link = NULL;
			size++;
		} else {
			last->link = next;
			last = next;
			last->link = NULL;
			size++;
		}
	}
	template< typename T >
	void LinkedList<T>::add(T nextData) {
		node<T> *next = new node<T>;
		next->data = nextData;
		next->link = NULL;
		
		if(first == NULL) {
			first = next;
			last = next;
			last->link = NULL;
			size++;
		} else {
			last->link = next;
			last = next;
			last->link = NULL;
			size++;
		}
	}
	// End list modifying functions.

	// Begin get/set functions.
	template< typename T >
	T LinkedList<T>::get(int pos) {
		if(pos > size) {
			cout << "That position is out of bounds." << endl;
		} else {
			int i = 0;
			node<T> *current;

			for(current = first;current != NULL;current = current->link) {
				if(i == pos) {
					return current->data;
				}
				i++;
			}
		}
		return 0;
	}
	template< typename T >
	void LinkedList<T>::set(int pos, T newData) {
		if(pos > size) {
			cout << "That position is out of bounds." << endl;
		} else {
			int i = 0;
			node<T> *current;

			for(current = first;current != NULL;current = current->link) {
				if(i == pos) {
					current->data = newData;
				}
				i++;
			}
		}
	}
	// End get/set functions.

	// Begin size-based functions.
	template< typename T >
	int LinkedList<T>::length() {
		return size;
	}
	template< typename T >
	bool LinkedList<T>::isEmpty() {
		return (first == NULL);
	}
	// End size-based functions.

	// Begin position-based functions.
	template< typename T >
	T LinkedList<T>::begin() {
		if(!isEmpty()) {
			return first->data;
		} else {
			return NULL;
		}
	}
	template< typename T >
	T LinkedList<T>::end() {
		if(!isEmpty()) {
			return last->data;
		} else {
			return NULL;
		}
	}
	// End position-based functions.

	// Begin sort function/s.
	template< typename T >
	void LinkedList<T>::sort(bool asc) {
		if(!isEmpty()) {
			node<T> *i;
			node<T> *j;

			for(i = first;i != NULL;i = i->link) {
				for(j = i->link;j != NULL;j = j->link) {
					if(asc) {
						if(j->data < i->data) {
							swap(i, j);
						}
					} else {
						if(j->data > i->data) {
							swap(i,j);
						}
					}
				}
			}
		}
	}
	template< typename T >
	void LinkedList<T>::swap(node<T> *i, node<T> *j) {
		T tempData = i->data;
		i->data = j->data;
		j->data = tempData;
	}
	// End sort function/s.

	// Begin print functions.
	template< typename T >
	void LinkedList<T>::printList() {
		if(!isEmpty()) {
			node<T> *current;

			for(current = first;current != NULL;current = current->link) {
				cout << current->data << " ";
			}
			cout << endl;
		} else {
			cout << "The list is empty." << endl;
		}
	}
	template< typename T >
	void LinkedList<T>::printElem(int pos) {
		if(pos > size) {
			cout << "That position is out of bounds." << endl;
		} else {
			int i = 0;
			node<T> *current;

			for(current = first;current != NULL;current = current->link) {
				if(i == pos) {
					cout << current->data << endl;
					break;
				}
				i++;
			}
		}
	}
	// End print functions.
	// End LinkedList class definitions.
}
// End linklist namespace.

#endif 

[hamsterman]

There should be no such problems either way. What error did you get and what was in your main?

[guestgulkan]

I think the OP may be confused bewteen the use of the terms typename and class when applied to template parameters.

[helios]

The template and class keywords are equivalent in every way when inside a template parameter list declaration.

[packetpirate]

When it was set to < class T > and I tried creating the list like this:

LinkedList<int> *myList = new LinkedList<int>();

...it said that "typename is not allowed".

[hamsterman]

Try compiling this

template<class T>
class C{
    T* c;
};

int main(){
    C<int> *cc = new C<int>();
    return 0;
}