Cyclic dependency between header files

Question

I\'m trying to implement a tree-like structure with two classes: Tree and Node. The problem is that from each class I want to call a function of th

Answer 1

Following the hints, here is the complete solution.

Tree.h:

#ifndef TREE_20100118
#define TREE_20100118

#include "Node.h"
#include 

class Tree
{
    int counter_;
    std::vector nodes_;

public:

    Tree();
    void start();
    void incCnt();
    void decCnt();
};

#endif /* TREE_20100118 */

Tree.cpp:

#include "Tree.h"
#include "Node.h"

Tree::Tree() : counter_(0) {}

void Tree::start()
{
    for (int i=0; i<3; ++i) {
        Node node(this, i);
        this->nodes_.push_back(node);
    }
    nodes_[0].hi();    // calling a function of Node
}

void Tree::incCnt() {
    ++counter_;
}

void Tree::decCnt() {
    --counter_;
}

---

Node.h:

#ifndef NODE_20100118
#define NODE_20100118

class Tree;

class Node
{
    Tree * tree_;
    int id_;

public:

    Node(Tree * tree, int id);
    ~Node();
    void hi();
};

#endif /* NODE_20100118 */

Node.cpp:

#include "Node.h"
#include "Tree.h"

#include 

Node::Node(Tree * tree, int id) : tree_(tree), id_(id)
{
    tree_->incCnt();    // calling a function of Tree
}

Node::~Node() {
    tree_->decCnt();
}

void Node::hi() {
    std::cout << "hi (" << id_ << ")" << std::endl;
}