#include <iostream>

using namespace std;

int main()
{
  double PV(double T, double n = 1.0); // default values here 
  double PV1 = PV(298.0);
  cout << "PV for n=1 and T=298 is " << PV1 << " atm*L" << endl;
  double PV2 = PV(298.0, 2.0); // this time don't use default n 
  cout << "PV for n=2 and T=298 is " << PV2 << " atm*L" << endl;
  return 0;
}

// function computes pressure-volume product PV = nRT, given T and n
// T is in Kelvin, n is in moles, and P*V is in atmospheres * Liters
double PV(double T, double n) // default values not here again
{
   double R = 0.08206; // in L*atm/(mol*K)
   double PV = n * R * T;
   return(PV);
}