The function doesn't add anything to my bst tree - c++

Question

class node{
public:
int data;
node *left;
node *right;
};
class BFStree{
public:
void insert(int key);
void deleteNode(int key);
void inorderTraversal(node *temp);
void inorder();
node *root;
BFStree(){
root = NULL;
}
};
void BFStree::insert(int key){
node *temp = root;
while(temp!=NULL){
if(key>temp->data){
temp = temp->right;
}
else if(key<temp->data){
temp = temp->left;
}
else{
cout << "NOT ALLOWED TO HAVE SAME DATA" << temp->data << " " << key << endl;
}
}
node *temp2 = new node;
temp2->data = key;
cout << key << " inserted" << endl;
temp2->left = NULL;
temp2->right = NULL;
temp = temp2;
}
int main(){
BFStree t;
t.insert(7);
t.insert(3);
t.insert(21);
}
I am trying to use the above function to insert data into the bst tree but it doesn't do anything, even the root is NULL
but when I use the following function, the job is accomplished. I don't understand what I have done differently in the two codes. I am new to programming so I am having such bad doubts. Please help me clear it.
void BFStree::insert(int key){
node *temp = root;
if(temp==NULL){
temp = new node;
temp->data = key;
temp->left = NULL;
temp->right = NULL;
root = temp;
return;
}
while(1){
if(key>temp->data){
if(temp->right==NULL){
node *temp2 = new node;
temp2->data = key;
temp2->left = NULL;
temp2->right = NULL;
temp->right = temp2;
break;
}
else{
temp = temp->right;
}
}
else if(key<temp->data){
if(temp->left==NULL){
node *temp2 = new node;
temp2->data = key;
temp2->left = NULL;
temp2->right = NULL;
temp->left = temp2;
break;
}
else{
temp = temp->left;
}
}
}
}

Answer 1

The main problem in your first function is that you just iterate over the tree until you find a null, and after that you assign that null value to temp.
After that you create a new node and assign temp the reference of new node. But your temp node is not connected to the tree. And there is no connection between the temp node and its parent or root node of the tree.
Whereas in 2nd example :
if(temp->right==NULL){
node *temp2 = new node;
temp2->data = key;
temp2->left = NULL;
temp2->right = NULL;
temp->right = temp2;
break;
}
This is the key, you store the reference of your newly created node in the right or left child of its parent node.