Code:
#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;

// function prototype
bool read(double &, double &, int &);
double calculateFutureValue(double &, double &, int &);
void displayValues(double &, double &, int &, double &);

int main()
{
double presentValue, interestRate, futureValue;
int months;
bool read_ret_value;

read_ret_value = read(presentValue, interestRate, months);
if(read_ret_value){
interestRate = interestRate/100;
futureValue = calculateFutureValue(presentValue, interestRate, months);
interestRate *= 100;
displayValues(presentValue, interestRate, months, futureValue);
}
else{
cout << endl << "one or more of the above values are not greater than zero";
}

return 0;
}

bool read(double& presentValue, double& interestRate, int& months)
{
cout << endl << "Enter present value, interest rate and number of months? ";
cin >> presentValue >> interestRate >> months;

if(presentValue > 0 && interestRate > 0 && months > 0)
return true;
else
return false;
}

double calculateFutureValue(double& presentValue, double& interestRate, int& months)
{
return presentValue * pow((1 + interestRate), months);
}

void displayValues(double& presentValue, double& interestRate, int& months, double& futureValue)
{
cout << endl << "Future Value" << setw(20) << "Present Value" << setw(20) << "Monthly Interest" << setw(20) << "Months";
cout << std::fixed;
cout << std::setprecision(2);
cout << endl << futureValue << setw(20) << presentValue << setw(20) << interestRate << setw(20) << months;

}