#include<iostream>

#include<fstream>

#include<cmath>

#include<string>

#include<iomanip>

using namespace std;

//Function to calculate the future value and return the same



double calculateFutureValue(double presentValue, double interestRate, int months){

   double futureValue = (double)presentValue * pow( (1 + interestRate), months);

   return futureValue;

}

//Function to read the input file and assign the value to the variables



unsigned int readfile(ifstream &inF, double &presentValue, double &interestRate, int &months){
   inF >> presentValue;
   inF >> interestRate;
   inF >> months;

   if(presentValue <= 0 || interestRate <= 0 || months <= 0){

      return 2;

   }

   else if( !(presentValue <= 0 || interestRate <= 0 || months <= 0)){

      return 1;
   }
   else{

      if(inF.eof()){

         return 0;
      }

   }

}

//Function to write data to file

void write2File(ofstream &of, double futureValue, double presentValue, double interestRate, int months){
   of << futureValue << "\t" << presentValue << "\t" << interestRate << "\t" << months << "\n";
}

// main function

int main(void){
   string infile;
   cout << "Enter the filename you want to process: ";
   cin >> infile;
   cout << endl;
   ifstream inF;
   inF.open(infile.c_str());
   if(!inF){
      cout << "File " << infile << " could not be opened" <<endl;
      return -1;
   }
   string outfile = "output.xls";
   ofstream of;
   of.open(outfile.c_str());
   if(!of){
      cout << "Error in creating the output file" << endl;
      return -1;
   }
   of << "Future Value\tPresent Value\tMonthly Interest\tMonths\n"; // printing header to output file
   double futureValue;
   double presentValue;
   double interestRate;
   int months;
   of << fixed << setprecision(2); // to print 2 places after decimal into file
   while(!inF.eof()){ // looping untill end of file
      int returnVal = readfile(inF, presentValue, interestRate, months);

      if(returnVal == 2){

         cout << presentValue << "\t" << interestRate << "\t" << months << endl;

         cout << "One or more of the above values are not greater than zero." << endl;

      }

      else if(returnVal == 1){

         futureValue = calculateFutureValue(presentValue, interestRate/100, months);

         write2File(of, futureValue, presentValue, interestRate, months);

      }

   }

   inF.close();

   of.close();

   return 1;

}