On 11/14/25 08:08, Alyssa Ross wrote: > Demi Marie Obenour writes: > >> On 11/13/25 13:01, Alyssa Ross wrote: >>> Demi Marie Obenour writes: >>> >>>> On 11/13/25 08:21, Alyssa Ross wrote: >>>>> Demi Marie Obenour writes: >>>>> >>>>>> + if (entry->d_name[0] == '.') >>>>>> + if (len == 1 || (len == 2 && entry->d_name[1] == '.')) >>>>>> + continue; >>>>>> + unsigned char c = (unsigned char)entry->d_name[0]; >>>>>> + if (!((c >= 'A' && c <= 'Z') || >>>>>> + (c >= 'a' && c <= 'z'))) >>>>>> + errx(EXIT_FAILURE, "Filename must begin with an ASCII letter"); >>>>> >>>>> Would the comparison not be valid without the cast? >>>> >>>> It would be in this case, but the subsequent cast to int in the error >>>> path assumes that the cast was done. Signed characters are much >>>> trickier and casting to unsigned makes the code easier to reason about. >>> >>> Is it safe to assume 'A' etc. are representable and comparable as >>> unsigned values? (I'm sure it is in practice, but I'd like it if I >>> could be confident this is being done strictly correctly.) >> >> I don't know if the C standard requires it, but we assume it. > > Is it a safe assumption, at least on all Linux architectures? I believe this assumption is hard-coded into GCC and Clang, so it's pretty safe. -- Sincerely, Demi Marie Obenour (she/her/hers)