#include "stdafx.h"
#include <iostream>
#include <sstream>
#include <string>
using namespace std;
#include "stack.h"

string postFix(string exp);

void main()
{
    string expression;
    cout<<"Enter An Infix Expression : ";

    getline(cin, expression);
    expression = postFix(expression);
    cout<<"\nPostfix expression is "<<expression<<"\n";
}

string postFix(string exp){
    Stack stack;
    char token;
    char * tokens;
    string postfixExp="", temp;
    int i = 0, var;
    for (int i=0; i<exp.length(); i++){
            token=exp[i];
            switch(token)
             {
                case ' ': break;
                case '(':
                    temp = token;
                    stack.push(temp);
                    break;
                case ')':
                    temp = stack.pop();
                    token = temp[0];
                    do{
                        postfixExp.append(1,token);
                        temp = stack.pop();
                        token = temp[0];
                    }while(token != '(');
                    break;
                case '+':
                    temp = token;
                    stack.push(temp);
                    break;
                case '-':
                    temp = token;
                    stack.push(temp);
                    break;
                case '*':
                    temp = token;
                    stack.push(temp);
                    break;
                case '/':
                    temp = token;
                    stack.push(temp);
                    break;
                default:
                    postfixExp=postfixExp.append(1,token);
                    break;
                }
            i++;
            }
    stack.display();
    temp = stack.pop();
    return postfixExp;
}