C

int
compare_doubles (const double *a, const double *b)
{
  double temp = *a - *b;
  if (temp > 0)
    return 1;
  else if (temp < 0)
    return -1;
  else
    return 0;
}
main()
{
  double *array;
  int size;
  ...
  qsort (array, size, sizeof (double), compare_doubles);
}

#define COMMAND(NAME)  { #NAME, NAME ## _command }
     
struct command commands[] =
{
       COMMAND (quit),
       COMMAND (help),
       ...
};