template errors

Code:

---

template<class Type>
class Tree
{
private:
  struct Node
  {
    Type item;
    //  node[0] = parent;
    //  node[1] = left child;
    //  node[2] = right child;
    Node * node[3];
  };
 
  Node * root;
public:
  Tree():root(NULL) {}
  Node* search_tree(Type x);
 
 
   
};

template<class Type>
Tree<Type>::Node *  Tree<Type>::search_tree(Type x)
{
  if( this == NULL) return NULL;
  if(this->item == x)
    return this;
  else if( this->item < x )
    return this->node[1].search_tree(x);
  else
    return this->node[2].search_tree(x);
}

---

That class template keeps giving me the errors;

Code:

---

error: expected constructor, destructor, or type conversion before ‘*’ token

---

does anyone know how to fix that error?

Code:

---

template<class Type>
typename Tree<Type>::Node *  Tree<Type>::search_tree(Type x)

---

In rough terms, without the typename keyword present, the standard says that the compiler must interpret TreeType<Node> as a non-type name while parsing the template code. That is the reason for your error message.

As to the reason the standard says that - view finding and understanding that as a homework challenge. The reason is not trivial, and a complete explanation gives most people a headache.

Thank you grumpy for the answer. I keep forgetting the use of "typename" for a user-defined type inside a class.