How to silence a particular “pointless comparison of unsigned with zero” warning?

Question

Suppose I have a function like the following:

#define LOWER_BOUND 0
#define UPPER_BOUND 42

int is_value_in_range( some_typedef val)
{
    return ((LOWER_BOU         


        

Answer 1

If some_typedef is not known to be unsigned or signed, I think you're pretty much out of luck.

If you know in advance that some_typedef is unsigned, you could just use

#if LOWER_BOUND > 0
    return ((LOWER_BOUND <= val) && (val <= UPPER_BOUND));
#else
    return ((val <= UPPER_BOUND));
#endif

Or in this case, you could use my preferred version:

    return (val-LOWER_BOUND <= UPPER_BOUND-LOWER_BOUND);

Edit: I'm going to assume if some_typedef is not known to be of particular signedness, then UPPER_BOUND and LOWER_BOUND must both be positive. Otherwise you would have very wacky results from some_typedef getting promoted to unsigned. Thus, you could always safely use:

    return ((uintmax_t)val-LOWER_BOUND <= UPPER_BOUND-LOWER_BOUND);