/* kertaus 6 */

#include <stdio.h>

void swap(double *x, double *y);

main()
{
  double a = 1, b = 2;
  printf("a = %lf, b = %lf\n", a, b);
  swap(&a, &b);
  printf("a = %lf, b = %lf\n", a, b);
}

void swap(double *x, double *y)
{
  double temp;
  temp = *x;
  *x = *y;
  *y = temp;
}