pr0524.cpp

practice c++, it is from the book http://www.amazon.com/Schaums-Outline-Programming-John-Hubbard

//  Programming with C++, Second Edition, by John R. Hubbard
//  Copyright McGraw-Hill, 2000
//  Problem 5.24 on page 114
//  A Function that Computes Formulas for Circles

#include <iostream>  // defines the cin and cout objects
using namespace std;
void computeCircle(double& area, double& circ, double r);

int main()
{ double a, c, r;
  cout << "Enter the radius: ";
  cin >> r;
  computeCircle(a,c,r);
  cout << "The area of a circle of radius " << r << " is " << a
       << "\nand its circumference is " << c << endl;
}

void computeCircle(double& area, double& circ, double r)
{ const double PI=3.141592653589793;
  area = PI*r*r;
  circ = 2*PI*r;
}