For given expression eg. a-b*c-d/e+f construct inorder sequence and traverse it using postorder traversal(non recursive).

#include<iostream>
#include<stack>
using namespace std;
//////////////////////////////////////////////////////////////
// //
//   Name : Vivek S. Sharma //
// Title : BST Expression Conversion //
// //
// //
//////////////////////////////////////////////////////////////
class Btree{
typedef struct node{
int data;
struct node * right ,*left;
}node;

public :
node * root,*temp;
Btree(){
root=new node;
root=NULL;
}
void create(){
temp=new node;

cout<<"\nEnter the data : ";
cin>>temp->data;
temp->left=temp->right=NULL;
if(root==NULL){
root=temp;
}
else{
insert(root,temp);
}
}

void insert(node * root, node * temp){
char ch;
cout<<"\nDo u want to enter "<<temp->data<<" as left or rright child of "<<root->data<<" : ";
cin>>ch;
if(ch=='l'){
if(root->left==NULL){
root->left=temp;
}
else
insert(root->left,temp);
}
else{
if(root->right==NULL)
root->right=temp;
else
insert(root->right,temp);
}

}
void postOrder_recursive(node * root){
if(root!=NULL){
postOrder_recursive(root->left);
postOrder_recursive(root->right);
cout<<"\t "<<root->data;
}
}
void postOrder_nonRecursive(node* root){
if(!root)
{
cout<<"\nEmpty";
return;
}
stack<node *> s;
stack<node*> p;
s.push(root);
while(!s.empty()){
node * cur=s.top();
p.push(cur);
s.pop();
if(cur->left)
s.push(cur->left);
if(cur->right)
s.push(cur->right);
}
while(!p.empty()){
cout<<"\t"<<p.top()->data;
p.pop(); }
}
//Extra Part : Inorder
void InOrder_nonRecursive(node* root){
if(!root)
{
cout<<"\nEmpty";
return;
}
stack<node *> s;
stack<node*> p;

while(true){
while(root!=NULL){
//cout<<"\t "<<root->data;
s.push(root);
root=root->left;
}
if(s.empty())
return;
root=s.top();
s.pop();

cout<<"\t "<<root->data;
root=root->right;
}
}
//Extra Part : PreOrder
void PreOrder_nonRecursive(node* root){
if(!root)
{
cout<<"\nEmpty";
return;
}
stack<node *> s;
stack<node*> p;

while(true){
while(root!=NULL){
cout<<"\t "<<root->data;
s.push(root);
root=root->left;
}
if(s.empty())
return;
root=s.top();
s.pop();

//cout<<"\t "<<root->data;
root=root->right;
}
}
void display(node* root, int space){

if(root==NULL)
return ;
space +=3;
display(root->right,space);
cout<<"\n";
for(int i=3; i<=space ; i++){
cout<<"  ";}
cout<<root->data<<"\n";
display(root->left,space);
}

};
int main(){
Btree b;
int ch;
do{
b.create();
cout<<"\nDo u wnat to insert more elements :1/0 ";
cin>>ch;

}while(ch!=0);
b.display(b.root,0);
cout<<"\nRecursive Post Order : ";
b.postOrder_recursive(b.root);
cout<<"\nNon Recursive Post Order : ";
b.postOrder_nonRecursive(b.root);
cout<<"\nNon Recursive In Order : ";
b.InOrder_nonRecursive(b.root);
cout<<"\nNon Recursive Pre Order : ";
b.PreOrder_nonRecursive(b.root);
return 0;
}