Print Binary Tree

#include <iostream>
#include "bintree.h"
#include <cstdlib>
#include <queue>

using namespace std;
using namespace main_savitch_10;

template <typename T>
	void display_complete_tree (const binary_tree_node<T>* t) {

		if (t == NULL)
			return;

		queue<const binary_tree_node<T>* > q;

		q.push(t);

		while (q.empty() == false) {

			int size = q.size();

			while (size > 0) {

			const binary_tree_node<string> *node = q.front();

			cout << node->data() << " ";

				q.pop();

				if (node->left() != NULL) {

					q.push(node->left());

				} else if (node->left() == NULL && node->right() != NULL){

					cout << "NULL ";

				}

				if (node->right() != NULL) {

					q.push(node->right());

				} else if (node->right() == NULL && node->left() != NULL){

					cout << "NULL ";

				}

				size--;

			}

        cout << endl;

		}

	}


binary_tree_node<string>* create_int_tree()
{
  binary_tree_node<string>* t1 = new binary_tree_node<string>("14");
  binary_tree_node<string>* t2 = new binary_tree_node<string>("32");
  binary_tree_node<string>* t3 = new binary_tree_node<string>("6");
  binary_tree_node<string>* t4 = new binary_tree_node<string>("23", NULL, t1);
  binary_tree_node<string>* t5 = new binary_tree_node<string>("9", t2, t3);
  binary_tree_node<string>* t6 = new binary_tree_node<string>("17", t4, t5);
  return t6;
}

int main()
{
    binary_tree_node<string>* t = create_int_tree();
    display_complete_tree(t);
    return EXIT_SUCCESS;
}


// returned: root of binary tree of integers