1  #include <math.h>
       2  #include <stdio.h>
       3  
       4  int main ()
       5  {
       6    double a = 1.0/0.0;
       7  
       8    if (! isfinite (a))
       9      printf ("infinity detected\n");
      10  
      11    a = 1.0/1.0;
      12  
      13    if (isfinite (a))
      14      printf ("number is now finite\n");
      15    return 0;
      16  }