C++ program for creation and traversal of a Binary Tree

A Simple CPP program for creation a binary tree and understand traversal of that tree.

#include<iostream.h> #include<conio.h> #include<process.h> struct tree_node { tree_node *left; tree_node *right; int data; } ; class bst { tree_node *root; public: bst() { root=NULL; } int isempty() { return(root==NULL); } void insert(int item); void inordertrav(); void inorder(tree_node *); void postordertrav(); void postorder(tree_node *); void preordertrav(); void preorder(tree_node *); }; void bst::insert(int item) { tree_node *p=new tree_node; tree_node *parent; p->data=item; p->left=NULL; p->right=NULL; parent=NULL; if(isempty()) root=p; else { tree_node *ptr; ptr=root; while(ptr!=NULL) { parent=ptr; if(item>ptr->data) ptr=ptr->right; else ptr=ptr->left; } if(item<parent->data) parent->left=p; else parent->right=p; } } void bst::inordertrav() { inorder(root); } void bst::inorder(tree_node *ptr) { if(ptr!=NULL) { inorder(ptr->left); cout<<" "<<ptr->data<<" "; inorder(ptr->right); } } void bst::postordertrav() { postorder(root); } void bst::postorder(tree_node *ptr) { if(ptr!=NULL) { postorder(ptr->left); postorder(ptr->right); cout<<" "<<ptr->data<<" "; } } void bst::preordertrav() { preorder(root); } void bst::preorder(tree_node *ptr) { if(ptr!=NULL) { cout<<" "<<ptr->data<<" "; preorder(ptr->left); preorder(ptr->right); } } void main() { bst b; b.insert(52); b.insert(25); b.insert(50); b.insert(15); b.insert(40); b.insert(45); b.insert(20); cout<<"inorder"<<endl; b.inordertrav(); cout<<endl<<"postorder"<<endl; b.postordertrav(); cout<<endl<<"preorder"<<endl; b.preordertrav(); getch(); }