/* program to compute the perimeter and area of a rectangle */

#include <stdio.h>

/* compute the perimeter and area of a rectangle, 
   given the lengths of the two sides */
void compute(double side1, double side2, double* pPerimeter, double* pArea)
{
  double lengthPlusWidth = side1 + side2;
  *pPerimeter = 2.0 * lengthPlusWidth;
  *pArea = side1 * side2;
}

/* demonstrate pointer passing by calling compute and displaying results */
int main()
{
  /* declare variables */
  double length = 5.0;
  double width  = 7.0;
  double perimeter;
  double area;

  /* print header */
  printf("working with a rectangle of width %lf and length %lf\n",
          width, length);
 
  /* compute desired quantities */
  compute(length, width, &perimeter, &area);

  /* print results */
  printf("the rectangle's perimeter is %lf\n", perimeter);
  printf("the rectangle's area is %lf\n", area);

  return 0;
}