Issue with Constructor of Struct nested in Class Template

Question

I need to turn a linked list class for ints that I wrote into a class template. I'm having issues with the constructor and destructor for a struct nested in the List Class, called node.

Layout:

  template <typename T>
  class List
  {
    public:
      //Stuff that's not important to this question
    private:
      struct Node
      {
        Node(T value);              // constructor
        ~Node();                // destructor
        Node *next;             // pointer to the next Node
        T data;               // the actual data in the node
        static int nodes_alive; // count of nodes still allocated
      };
  };

Implementation:

template <typename T>
typename List<T>::Node::Node(T value)
{
  data = value;
  next = 0;
}

template <typename T>
typename List<T>::Node::~Node()
{
   --nodes_alive;
}

Errors:

1. Expected ';' at end of declaration

   typename List::Node::Node(T value)

2. Expected an identifier or template ID after '::'

   typename List::Node::~Node()

3. Expected the class name after '~' to name a destructor

   typename List::Node::~Node()

Not really sure what's going on here. My implementation is in a separate file included at the bottom of the header file. Any help would be greatly appreciated.

Answer 1

It's simple: Get rid of the typename keyword. Since you're writing a constructor/destructor and there is no return type, it is not needed.

template <typename T>
List<T>::Node::Node(T value)
{
  data = value;
  next = 0;
}

template <typename T>
List<T>::Node::~Node()
{
   --nodes_alive;
}