#include <stdio.h>

void swap(float * x, float * y)
{
  float aux;
  aux = *x;
  *x = *y;
  *y = aux;
}

int main(void)
{
  double a = 3.5, b = 5.6;
  long long int *lla = &a, *llb = &b;
  printf("%llx %llx\n", *lla, *llb);
  swap(&a, &b);
  printf("%g %g\n", a, b);
  printf("%llx %llx\n", *lla, *llb);
  return 0;
}