#include <iostream>
#include <string>
#include <fstream>

using namespace std;

bool isOperator(char symbol)          //definition of isOperator
{
    if( (symbol == '*') || (symbol == '+')  || (symbol == '/')  || (symbol == '-' ) )
                        return true;
    else
                        return false;
}

class Stack {

 public:
   int MaxStack;
   int EmptyStack;
   char* items;
   int top;


   Stack(int);
   ~Stack();
   int TOP();
   void push(char);
   char pop();
   int empty();
   int full();

};
Stack::Stack(int size) {
   MaxStack = size;
   EmptyStack = -1;
   top = EmptyStack;
   items = new char[MaxStack];
}

Stack::~Stack() {delete[] items;}
int Stack::TOP(){
return items[top];
}
void Stack::push(char c) {
   items[++top] = c;
}

char Stack::pop() {
   return items[top--];
}

int Stack::full()  {
   return top + 1 == MaxStack;
}

int Stack::empty()  {
   return top == EmptyStack;
}



int main()
{
  cout <<"WELCOME TO PROJECT 4 PROGRAM"<<endl;

  // basic components
  string line;
  string outputLine;

  //stacks

  Stack stack(20);
  char c;


  ifstream myfile ("Prefix.in");
  if (myfile.is_open())
  {
    while ( myfile.good() )
    {
      getline(myfile,line);
      cout << line << endl;

    }
  }

  else cout << "Unable to open file";

//flags, operator method
while (line.length()!=0)    //while not end of blank line
            {
                   Stack flags(20);
                   Stack operators(20);

            for(int i=0; i < line.size(); i ++)  //reiterate through ‘line’
                        {
                          char symbol = line [i];
                          if( isOperator(symbol))    //if the symbol is an operator
                            {
                                operators.push(symbol);    //push operator on stack
                                 flags.push(0);  //push associated flag on stack
                                  }
                        if((symbol != ' ') && !isOperator(symbol))     //then it’s a operand
                            {
                              outputLine += symbol;                //append
                             while(flags.TOP())       //while top flag is ON on stack
                              {
                                outputLine += operators.TOP() ;  //append the associated op
                                operators.pop();   //remove operator from stack
                                flags.pop();     //remove flag from stack
                              }
                                flags.pop();                 //set next flag ON
                                flags.push(1);
                            }
                        }//end of for

                        if(!operators.empty() || (!flags.empty()) )
                        {
                                    cout << "SOMETHING WENT WRONG. Prob incorrect input" << endl;
                        }
                        else
                        {
                                    cout << line << endl;
                                    cout << outputLine << endl;
                        }
            } //end of while eof


  ofstream outfile ("Postfix.out");
  if (outfile.is_open())
  {
    outfile << outputLine << endl;
    outfile << line << endl;

    myfile.close();
  }
  else cout << "Unable to open file";
  myfile.close();
  //outFile.close();
  return 0;
}