Inf and NaN values handling in C.

inf.c

/*
 * $Id: $
 *
 * Module:  inf -- description
 * Created: 18-DEC-2007 19:17
 * Author:  tmr
 */

#define INF         (1.0 / 0.0)
#define NAN         (0.0 / 0.0)
#define IS_INF(x)   ((double) (x) == (INF))
#define IS_NINF(x)  (IS_INF (-(x)))
#define IS_NAN(x)   ((double) (x) == (NAN))

int main (int argc, char * argv []) {

  printf ("IS_INF  (+INF) -> %d\n", IS_INF  (+INF));
  printf ("IS_INF  (-INF) -> %d\n", IS_INF  (-INF));
  printf ("IS_INF  (   0) -> %d\n", IS_INF  (   0));
  printf ("IS_NINF (+INF) -> %d\n", IS_NINF (+INF));
  printf ("IS_NINF (-INF) -> %d\n", IS_NINF (-INF));
  printf ("IS_NINF (   0) -> %d\n", IS_NINF (   0));
  printf ("IS_NAN  (+NAN) -> %d\n", IS_NAN  (+NAN));
  printf ("IS_NAN  (-NAN) -> %d\n", IS_NAN  (-NAN));
  printf ("IS_NAN  (   0) -> %d\n", IS_NAN  (   0));
  printf ("+INF > 0       -> %d\n", +INF > 0);
  printf ("+INF < 0       -> %d\n", +INF < 0);
  printf ("-INF > 0       -> %d\n", -INF > 0);
  printf ("-INF < 0       -> %d\n", -INF < 0);
  printf ("+NAN > 0       -> %d\n", +NAN > 0);
  printf ("+NAN < 0       -> %d\n", +NAN < 0);
  printf ("-NAN > 0       -> %d\n", -NAN > 0);
  printf ("-NAN < 0       -> %d\n", -NAN < 0);

  return (0);
}

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