#include <iostream>
#include <cmath>
using namespace std;

// function prototype
double coneVolume( double r, double h );
void swap( double &a, double &b );

int main() {
  double r, h, v;
  cout << "enter radius of base of cone: ";
  cin >> r;
  cout << "enter height of cone: ";
  cin >> h;
  cout << "you entered: radius=" 
       << r << " height=" << h << endl;
  v = coneVolume( r,h );
  cout << "the volume of your cone is " 
       << v << endl;
  swap( r, h );
  cout << "swapped values: radius=" 
       << r << " height=" << h << endl;
  v = coneVolume( r,h );
  cout << "swapped volume of your cone is " 
       << v << endl;
} // end of main()


// define function
double coneVolume( double r, double h ) {
  double v;
  v = (1.0/3.0) * M_PI * pow( r,2 ) * h;
  return v;
} // end of coneVolume()

void swap( double &a, double &b ) {
  double tmp = a;
  a = b;
  b = tmp;
} // end of swap()