Making a binary search tree into a template - c++

Question

So, I've made a binary search tree, but now I'm stuck, as I have to make it into a template, yet my knowledge of templates are rather limited and if someone could, I'd appreciate it if they could "spoonfeed" me how to convert the tree into one that would work for any numerical data, thanks in advance!
Main.cpp
#include <iostream>
#include "bst.h"
using namespace std;
int main()
{
BST tree;
tree.insert(8);
tree.insert(25);
tree.insert(99);
tree.insert(20);
tree.insert(25);
tree.insert(20);
tree.insert(2);
tree.insert(89);
tree.insert(15);
tree.insert(10);
tree.insert(30);
tree.insert(50);
tree.displayorder();
int number;
int Inputnumber;
while (true){
cout << "Choose what you want to do: " << endl << "1# Insert" << endl << "2# Display Orders" << endl << "3# Search" << endl << "4# Delete" << endl << endl << endl;
cin >> Inputnumber;
if (Inputnumber==1){
cout << endl << "Enter the number you want inserted: ";
cin >> number;
tree.insert(number);
cout << endl << endl << endl;
}
if (Inputnumber==2){
cout<<"Display Orders: " << endl;
tree.displayorder();
cout << endl << endl << endl;
}
if (Inputnumber==3){
cout<<"Enter the number you want to search for: ";
cin >> number;
tree.search(number);
cout << endl << endl << endl;
}
if (Inputnumber==4){
cout << "Enter the number you want to remove: ";
cin >> number;
tree.remove(number);
cout << endl << endl << endl;
}
}
}
Bst.cpp
#include <iostream>
#include "bst.h"
using namespace std;
BST::node* BST::makeEmpty(node* tree)
{
if(tree == NULL)
return NULL;
{
makeEmpty(tree->left);
makeEmpty(tree->right);
delete tree;
}
return NULL;
}
BST::node* BST::insert(int x, node* tree)
{
if(tree == NULL)
{
tree = new node;
tree->data = x;
tree->left = tree->right = NULL;
}
else if(x < tree->data)
tree->left = insert(x, tree->left);
else if(x >= tree->data)
tree->right = insert(x, tree->right);
return tree;
}
BST::node* BST::findMin(node* tree)
{
if(tree == NULL)
return NULL;
else if(tree->left == NULL)
return tree;
else
return findMin(tree->left);
}
BST::node* BST::findMax(node* tree)
{
if(tree == NULL)
return NULL;
else if(tree->right == NULL)
return tree;
else
return findMax(tree->right);
}
BST::node* BST::remove(int x, node* tree)
{
node* temp;
if(tree == NULL)
return NULL;
else if(x < tree->data)
tree->left = remove(x, tree->left);
else if(x > tree->data)
tree->right = remove(x, tree->right);
else if(tree->left && tree->right)
{
temp = findMin(tree->right);
tree->data = temp->data;
tree->right = remove(tree->data, tree->right);
}
else
{
temp = tree;
if(tree->left == NULL)
tree = tree->right;
else if(tree->right == NULL)
tree = tree->left;
delete temp;
}
return tree;
}
void BST::inorder(node* tree)
{
if(tree == NULL){
return;
}
inorder(tree->left);
cout << tree->data << " ";
inorder(tree->right);
}
void BST::preorder(node* tree)
{
if(tree == NULL){
return;
}
cout << tree->data << " ";
inorder(tree->left);
inorder(tree->right);
}
void BST::postorder(node* tree)
{
if(tree == NULL){
return;
}
inorder(tree->left);
inorder(tree->right);
cout << tree->data << " ";
}
BST::node* BST::find(node* tree, int x)
{
if(tree == NULL)
return NULL;
else if(x < tree->data)
return find(tree->left, x);
else if(x > tree->data)
return find(tree->right, x);
else
return tree;
}
BST::BST()
{
root = NULL;
}
BST::~BST()
{
root = makeEmpty(root);
}
void BST::insert(int x)
{
root = insert(x, root);
}
void BST::remove(int x)
{
root = remove(x, root);
}
void BST::displayorder()
{
inorder(root);
cout << endl;
preorder(root);
cout << endl;
postorder(root);
cout << endl << endl;
}
void BST::search(int x)
{
if(root = find(root, x)){
cout << endl << "Found!" << endl;
}
else{
cout << endl << "Not Found!" << endl;
}
}
Bst.h
#ifndef BST_H
#define BST_H
class BST
{
struct node
{
int data;
node* left;
node* right;
};
node* root;
node* makeEmpty(node* tree);
node* insert(int x, node* tree);
node* findMin(node* tree);
node* findMax(node* tree);
node* remove(int x, node* tree);
void inorder(node* tree);
void preorder(node* tree);
void postorder(node* tree);
public:
BST();
~BST();
node* find(node* tree, int x);
void insert(int x);
void remove(int x);
void displayorder();
void search(int x);
};
#endif // BST_H

Answer 1

You could do that by using the following changes:
In your BST.h file, add the following above the class decleration:
template < typename T >
class BST {
[...]
}
Then, foreach method definition, change it to:
template < typename T >
typename BST<T>::node* BST<T>::makeEmpty(BST<T>::node* tree)
{
if(tree == NULL)
return NULL;
{
makeEmpty(tree->left);
makeEmpty(tree->right);
delete tree;
}
return NULL;
}
Then, search and replace int with T in both BST.h and BST.cpp.
And then in your main.cpp change the variable to BST<int> tree.
The result should be this:
#include <iostream>
using namespace std;
template < typename T >
class BST
{
struct node
{
T data;
node* left;
node* right;
};
node* root;
node* makeEmpty(node* tree);
node* insert(T x, node* tree);
node* findMin(node* tree);
node* findMax(node* tree);
node* remove(T x, node* tree);
void inorder(node* tree);
void preorder(node* tree);
void postorder(node* tree);
public:
BST();
~BST();
node* find(node* tree, T x);
void insert(T x);
void remove(T x);
void displayorder();
void search(T x);
};
template < typename T >
typename BST<T>::node* BST<T>::makeEmpty(BST<T>::node* tree)
{
if(tree == NULL)
return NULL;
{
makeEmpty(tree->left);
makeEmpty(tree->right);
delete tree;
}
return NULL;
}
template < typename T >
typename BST<T>::node* BST<T>::insert(T x, BST<T>::node* tree)
{
if(tree == NULL)
{
tree = new node;
tree->data = x;
tree->left = tree->right = NULL;
}
else if(x < tree->data)
tree->left = insert(x, tree->left);
else if(x >= tree->data)
tree->right = insert(x, tree->right);
return tree;
}
template < typename T >
typename BST<T>::node* BST<T>::findMin(BST<T>::node* tree)
{
if(tree == NULL)
return NULL;
else if(tree->left == NULL)
return tree;
else
return findMin(tree->left);
}
template < typename T >
typename BST<T>::node* BST<T>::findMax(BST<T>::node* tree)
{
if(tree == NULL)
return NULL;
else if(tree->right == NULL)
return tree;
else
return findMax(tree->right);
}
template < typename T >
typename BST<T>::node* BST<T>::remove(T x, BST<T>::node* tree)
{
node* temp;
if(tree == NULL)
return NULL;
else if(x < tree->data)
tree->left = remove(x, tree->left);
else if(x > tree->data)
tree->right = remove(x, tree->right);
else if(tree->left && tree->right)
{
temp = findMin(tree->right);
tree->data = temp->data;
tree->right = remove(tree->data, tree->right);
}
else
{
temp = tree;
if(tree->left == NULL)
tree = tree->right;
else if(tree->right == NULL)
tree = tree->left;
delete temp;
}
return tree;
}
template < typename T >
void BST<T>::inorder(BST<T>::node* tree)
{
if(tree == NULL){
return;
}
inorder(tree->left);
cout << tree->data << " ";
inorder(tree->right);
}
template < typename T >
void BST<T>::preorder(BST<T>::node* tree)
{
if(tree == NULL){
return;
}
cout << tree->data << " ";
inorder(tree->left);
inorder(tree->right);
}
template < typename T >
void BST<T>::postorder(BST<T>::node* tree)
{
if(tree == NULL){
return;
}
inorder(tree->left);
inorder(tree->right);
cout << tree->data << " ";
}
template < typename T >
typename BST<T>::node* BST<T>::find(BST<T>::node* tree, T x)
{
if(tree == NULL)
return NULL;
else if(x < tree->data)
return find(tree->left, x);
else if(x > tree->data)
return find(tree->right, x);
else
return tree;
}
template < typename T >
BST<T>::BST()
{
root = NULL;
}
template < typename T >
BST<T>::~BST()
{
root = makeEmpty(root);
}
template < typename T >
void BST<T>::insert(T x)
{
root = insert(x, root);
}
template < typename T >
void BST<T>::remove(T x)
{
root = remove(x, root);
}
template < typename T >
void BST<T>::displayorder()
{
inorder(root);
cout << endl;
preorder(root);
cout << endl;
postorder(root);
cout << endl << endl;
}
template < typename T >
void BST<T>::search(T x)
{
if(root = find(root, x)){
cout << endl << "Found!" << endl;
}
else{
cout << endl << "Not Found!" << endl;
}
}
int main()
{
BST<int> tree;
tree.insert(8);
tree.insert(25);
tree.insert(99);
tree.insert(20);
tree.insert(25);
tree.insert(20);
tree.insert(2);
tree.insert(89);
tree.insert(15);
tree.insert(10);
tree.insert(30);
tree.insert(50);
tree.displayorder();
int number;
int Inputnumber;
while (true){
cout << "Choose what you want to do: " << endl << "1# Insert" << endl << "2# Display Orders" << endl << "3# Search" << endl << "4# Delete" << endl << endl << endl;
cin >> Inputnumber;
if (Inputnumber==1){
cout << endl << "Enter the number you want inserted: ";
cin >> number;
tree.insert(number);
cout << endl << endl << endl;
}
if (Inputnumber==2){
cout<<"Display Orders: " << endl;
tree.displayorder();
cout << endl << endl << endl;
}
if (Inputnumber==3){
cout<<"Enter the number you want to search for: ";
cin >> number;
tree.search(number);
cout << endl << endl << endl;
}
if (Inputnumber==4){
cout << "Enter the number you want to remove: ";
cin >> number;
tree.remove(number);
cout << endl << endl << endl;
}
}
}