//This program demonstrates the use of reference parameters
//in computing the volume and surface area of a cylinder
//It also shows how to pass a file variable to a function
//No formatting has been done in this version of the program

const double PI = 3.141592;                 //global constant
#include <iostream>
#include <fstream>
using namespace std;

void getCyl(float &, float &);
void computeCylinder(float, float, float &, float &);
void writeResults(float volume, float surfArea);
void writeResultstoFile( ofstream &fout, float radius, float height, float volume, float surfArea);


int main()
{
   ofstream fout;
   fout.open("CYL.TXT");
   float radius, height;        //dimensions of the cylinder
   float radius2, height2;
   float volume, surfArea;
   float volume2, surfArea2;
   getCyl(radius, height);
   computeCylinder(radius, height, volume, surfArea);
   writeResults(volume, surfArea);
   writeResultstoFile(fout, radius, height, volume, surfArea);
   getCyl(radius2, height2);
   computeCylinder(radius2, height2, volume2, surfArea2);
   writeResults(volume2, surfArea2);
   writeResultstoFile(fout, radius2, height2, volume2, surfArea2);
   return 0;
}

/* getCyl() inputs the dimensions of a cylinder */
void getCyl( float & rad, float & ht)
{
    cout << "Enter the radius of a cylinder ";
    cin >> rad;
    cout << "Enter the height  of the cylinder ";
    cin >> ht;
}
/* computeCylinder() computes the volume and the surface area of a cylinder */
void computeCylinder(float rad, float ht, float &vol, float &surfArea)
{
 vol =  PI * rad * rad *ht;
 surfArea = 2*PI * rad * rad + 2*PI *rad* ht;
 //cout << rad << "  " << ht << "  " << vol << "  " << surfArea <<endl;
}
//writes computed results for the cylinder to the standard output device
void writeResults(float volume, float surfArea)
{
   cout << "The volume is "  << volume << endl;
   cout << "And surface area is "  << surfArea << endl;
}

//write computed results for the cylinder to a text file
void writeResultstoFile( ofstream & fout, float radius, float height, float volume, float surfArea)
{
   fout << "Height is "  << height << endl;
   fout << "Radius is "  << radius << endl;

   fout << "Volume is "  << volume << endl;
   fout << "Surface area is "  << surfArea << endl;
}