/* Peter Cline CISC 105, June 6 2007
 * 
 * calculates area of a circle
 */

#include <stdio.h>
#define PI 3.14159

// function prototype
void boasting();
void calculateArea(double rad);
void calculateCircumference(double rad);

int main() {
  double radius = 0;

  // function call
  boasting();

  printf("Enter a radius: ");
  scanf("%lf", &radius);

  calculateArea(radius); 
  radius = radius * 3;
  calculateCircumference(radius);

  return 0;
}

// function definition
// prints a proud message about this program
void boasting()
{
  printf("This program is great!\n");
  printf("I hope you enjoyed using this awesome program.\n");
}

// calculates the area of a circle
void calculateArea(double rad) 
{
  double area;

  /* area is calculated by the formula: area = pi*r^2 */
  area = PI*rad*rad;

  printf("The area of the circle with the radius %lf is: %lf\n", rad, area);

}

// function definition
// this function calculates the circumference of a circle
// and prints out the value to the user
void calculateCircumference(double rad)
{
  double circ = 0;

  // circumference = 2 * PI * radius
  circ = 2 * PI * rad;

  printf("The circumference is %lf\n", circ);
}