Question

I am writing a C++ program that implements a Binary Search Tree (BST). So, I started off implementing a binary tree node as a struct. Since a binary tree node contains two pointers to other binary tree nodes, the struct includes pointers to variables of that struct type. For this, I understand that a forward declaration of the struct is needed. I’ve done that. Yet, I get a run-time error for the simple program below which does nothing but assign a value to a member of said struct. I don’t understand why. Please let me know the reason.

#include <iostream>
using namespace std;

struct t_node;

struct t_node
{
       int data;
       t_node* left;
       t_node* right;
};

int main()
{
    t_node *root;
    root->data = 2;

    cin.get();
    return 0;
}

I am using Dev-C++ 4.9.9.2.

Thanks!

Answer 1

You need to alocate memory for your node. Use new:

t_node* root = new t_node();