Insert function recreates root node - c++

Question

I'm trying to create a non-recursive insert() function. The only example I have in the book is a recursive one and I'm trying to convert it. Just so you have an idea of what I'm trying to accomplish and why I'll include the instructions.
Write a class for implementing a simple binary search tree capable of storing numbers. The class should have member functions:
void insert(double x)
bool search(double x)
void inorder(vector <double> & v)
The insert function should not use recursion directly or indirectly by calling a recursive function.
There is more, but I think this gives the idea behind what I'm asking about. As of now the function just keep recreating the root node. Here is what I have.
#include "stdafx.h"
#include <iostream>
#include <vector>
class BinaryTree {
private:
struct TreeNode {
double value;
TreeNode *left;
TreeNode *right;
TreeNode(double value1,
TreeNode *left1 = nullptr,
TreeNode *right1 = nullptr) {
value = value1;
left = left1;
right = right1;
}
};
TreeNode *root; //pointer to the root of the tree
bool search(double x, TreeNode *t) {
while (t) {
std::cout << "running through t." << std::endl;
if (t->value == x) {
return true;
}
else if (x < t->value) {
std::cout << "wasn't found, moving left." << std::endl;
search(x, t->left);
}
else {
std::cout << "wasn't found, moving right." << std::endl;
search(x, t->right);
}
}
std::cout << "wasn't found." << std::endl;
return false;
}
public:
std::vector<TreeNode> v;
BinaryTree() {
root = nullptr;
}
void insert(double x) {
TreeNode *tree = root;
if (!tree) {
std::cout << "Creating tree." << x << std::endl;
root = new TreeNode(x);
return;
}
while (tree) {
std::cout << "Adding next value." << std::endl;
if (tree->value == x) return;
if (x < tree->value) {
tree = tree->left;
tree->value = x;
}
else {
tree = tree->right;
tree->value = x;
}
}
}
bool search(double x) {
return search(x, root);
}
/*void inOrder(TreeNode *v) const {
while (root != nullptr) {
inOrder(root->left);
v.push_back(root->value);
inOrder(root->right);
v.push_back(root->value);
}
}*/
};
int main() {
BinaryTree t;
std::cout << "Inserting the numbers 5, 8, 3, 12, and 9." << std::endl;
t.insert(5);
t.insert(8);
t.insert(3);
t.insert(12);
t.insert(9);
std::cout << "Looking for 12 in tree." << std::endl;
if (t.search(12)) {
std::cout << "12 was found." << std::endl;
}
std::cout << "Here are the numbers in order." << std::endl;
return 0;
}

Answer 1

You have to add one more level of dereference if you want your code to work. And of course create the new node at the end of the function. The following code should work:
void insert(double x) {
TreeNode **tree = &root;
while (*tree) {
std::cout << "Adding next value." << std::endl;
if ((*tree)->value == x) return;
if (x < (*tree)->value) {
tree = &(*tree)->left;
} else {
tree = &(*tree)->right;
}
}
if (!(*tree)) {
std::cout << "Creating tree." << x << std::endl;
*tree = new TreeNode(x);
return;
}
}
And your search method should looks like:
bool search(double x) {
TreeNode *node = root;
while (node) {
if (node->value == x) {
return true;
} else if (x < node->value) {
node = node->left;
} else {
node = node->right;
}
}
std::cout << "wasn't found." << std::endl;
return false;
}
Result of your main function, with my code:
Inserting the numbers 5, 8, 3, 12, and 9.
Creating tree.5
Adding next value.
Creating tree.8
Adding next value.
Creating tree.3
Adding next value.
Adding next value.
Creating tree.12
Adding next value.
Adding next value.
Adding next value.
Creating tree.9
Looking for 12 in tree.
12 was found.