c++ how to assign a pointer to a parent in a binary tree

Question

i'm confused on how you initialize the m_parent to point to the node above the child.

    class Node
{
public:
    Node(string city);
    ~Node();
    string m_city;
    int m_parent_distance;
    Node *m_left;
    Node *m_right;
    Node *m_parent;
};
Node *m_root;
//void test_print(string target, Node *cur_root);
Node * find_node(Node *m_root, string target);

this is the node constructor

    Stree::Node::Node(string city)
{
    m_city = city;
    m_left = NULL;
    m_right = NULL;
    //what do i do with m_parent??
    m_parent_distance = 0;
}

Answer 1

Pass the parent as a parameter to your constructor, and initialize it from there:

class Node
{
public:
    Node(string city, Node *parent);
    ~Node();
    string m_city;
    int m_parent_distance;
    Node *m_left;
    Node *m_right;
    Node *m_parent;
};

Stree::Node::Node(string city, Node *parent)
    : m_city(city),
      m_left(NULL),
      m_right(NULL),
      m_parent(parent),
      m_parent_distance(0)
{
}

By the way, you should use an initializer list (like I wrote above) rather than assignments in the constructor (like the code you showed us).