#include <iostream>
#include <iomanip>
#include <math.h>
#include <cmath>

double getAmount(double);                           //function 1
double roundAmount(double);                        //function 2
double calcAverage_exact(double, int);           //function 3.1
double calcAverage_round(int, int);                //function 3.2
double calcStdDev_exact(double, double, int); //function 4.1
double calcStdDev_round(int, int, int);           //function 4.2
double calcDiff(double, double);                    //function 5
using namespace std;
int main()
{
    double money;
    int round_money;
    double exact_sum = 0;
    double in_sum;
    int round_sum = 0;
    double exact_squares = 0;
    int round_squares;
    int count_money = 0;
    double sumsquares_exact = 0;
    int sumsquares_round = 0; 
    
    cout<< "\nEnter an amount (0 to quit):";
    cin>> money;
while(money > 0)
{
    count_money ++;
    exact_sum += money;
    money = getAmount(money);
    round_money = (int) roundAmount(money);
    round_sum += round_money;
    exact_squares = money * money;
    sumsquares_exact += exact_squares;
    round_squares = round_money * round_money;
    sumsquares_round += round_squares;

cout<< "\nEnter an amount (0 to quit) :";
cin>> money;
}

cout<<setiosflags(ios::fixed|ios::showpoint)<<setprecision(2);

double average_exact;
double stddev_exact;
double prct_dif;
int average_round;
int stddev_round;

average_exact = calcAverage_exact(sumsquares_exact, count_money);
average_round = (int) calcAverage_round(sumsquares_round, count_money);
stddev_exact = calcStdDev_exact(exact_sum, sumsquares_exact, count_money);
stddev_round = (int) calcStdDev_round(round_sum, sumsquares_round, count_money);
prct_dif = calcDiff(exact_sum, round_sum);

if(average_exact == -1 or average_round == -1)
cout<<"\nnot enough values to calculate the average";
if(stddev_exact == -1 || stddev_round == -1)
cout<<"\nnot enough values to calculate the standard deviation";
else

 cout<<"\nCalculation     Exact       Round";
 cout<<"\n--------------------------------------";

 cout<<"\nSum:"
               <<setw(17)
               <<exact_sum
               <<setw(12)
               <<round_sum;  
                      
cout<<"\nAverage:"
                  <<setw(13)
                  <<average_exact
                  <<setw(12)
                  <<average_round;

cout<<"\nStd Dev:"
                  <<setw(13)
                  <<stddev_exact
                  <<setw(12)
                  <<stddev_round;

if (prct_dif <= 2)
{
   cout<<"\nIts cost effective!\n";

   system ("pause");
   return 0;
}

else
    cout<<"\nIts not cost effective!\n";
    
    system ("pause");
    return 0;
}

// Function 1
double getAmount(double money)
{
if (money > 0)
{
      return money;
}     
else
if (money < 0)
{
      cout<<"\nPlease enter a valid number";
      cin>>money;
      return money;
}

else
      return 0;
}

// Function 2

double roundAmount(double money)
{ 
       double in_sum;
       int round_money;
       in_sum = (money + 5) / 10;
       round_money = (int) in_sum * 10;
       return round_money;
}
       
// Function 3.1

double calcAverage_exact(double exact_sum, int count_money)
{
       double average_exact;
       if (count_money > 1)       
       {
       average_exact = exact_sum / count_money ;
       return average_exact;;
       }
       else
       return -1;
}

// Function 3.2

double calcAverage_round(int round_sum, int count_money)
{
       double average_round;
       if (count_money > 1)       
       {
       average_round = round_sum / count_money;
       return average_round;
       }
       else
       return -1;
}

// Function 4.1

double calcStdDev_exact(double exact_sum, double sumsquares_exact, int count_money)
{
       double stddev_exact;
       if (count_money > 1)
       {
        stddev_exact = sqrt((sumsquares_exact - (exact_sum * exact_sum / count_money))/(count_money - 1));
        return stddev_exact;
       }           
       else
       return -1;
}

//Function 4.2

double calcStdDev_round(int round_sum, int sumsquares_round, int count_money)
{
       int stddev_round;
       if (count_money > 1)
       {
        stddev_round = (int) sqrt((sumsquares_round - (round_sum * round_sum / count_money))/(count_money - 1));
        return stddev_round;
       }           
       else
       return -1;
}

//Function 5

double calcDiff(double exact_sum, double round_sum)
{
       double prct_dif;
       prct_dif = ((fabs(exact_sum - round_sum))/exact_sum) * 100;
       return prct_dif;
}

double calcAverage_exact(double exact_sum, int count_money)
{
       double average_exact;
       if (count_money > 1)       
       {
       average_exact = exact_sum / (double)count_money ;
       return average_exact;;
       }
       else
       return -1;
}

double calcAverage_exact(double exact_sum, int count_money)
{
if (count_money) return (exact_sum / (double)count_money);
else return -1;
}