Question

I have been doing some research about this and have found a few similar questions on stackoverflow talking about the visibility of types, but this doesn’t seem to be exactly the same problem (or at least that’s what I think after some hours working on it).

Let’s focus:

The problem

C++ compiler reports “abc.cpp:132: error: expected constructor, destructor, or type conversion before ‘*’ token”

The code where the problem is reported

template <class C, class I> ABC<C, I>::Node * ABC<C, I>::buscaTreuIRetornaMinim(Node **node) {
    if (*node == NULL) return NULL;
    if ((*node)->fesq != NULL) return buscaTreuIRetornaMinim(&(*node)->fesq);
    Node *q = *node;
    *node = *node->fdre;
    return q;
}

The problem is reported on the first line, the function header. So far, I understand the problem is when specifying ‘Node *’ but it’s already fully qualified so I don’t see where’s the problem.

The rest of the class definition

class ABC {
public:
    ABC(void) : arrel(NULL), numelements(0), altura(0) { }
    void inserir(C pclau, I pinfo);
    void inordre(void);
    I consultar(C pclau);
    C minim(void);
    C maxim(void);
    void esborrar(C pclau);

private:
    class Node {
    public:
        C clau;
        I info;
        Node *fesq;
        Node *fdre;

        Node(C pclau, I pinfo, Node *pfesq = NULL, Node *pfdre = NULL) : clau(pclau), info(pinfo), fesq(pfesq), fdre(pfdre) { }
    };

    Node *arrel;
    Node *actual;
    int numelements;
    int altura;

    void inserir(C pclau, I pinfo, Node **node);
    void inordre(Node **node);
    I consultar(C pclau, Node **node);
    C minim(Node **node);
    C maxim(Node **node);
    void esborrar(C pclau, Node **node);
    Node * buscaTreuIRetornaMinim(Node **node);
};

On the other hand, I can ensure the rest of the functions are fully functional. That’s the only problem I have dealt with so far.

Any tip will be greatly appreciated. Thanks in advance for your time.

Answer 1

A qualified type name that includes template parameters must be prefixed with the keyword typename : typename ABC<C, I>::Node *

You can read more about about the necessity of this typename keyword here.