> > if (c >= 'a' && c <= 'z')
>
> This relies on ASCII being used, which I think should be mentioned.
> Somewhat
> related, but C2Y is standardizing sequential hex digits so case'a'...'f'
> and
> case'A'...'F' will work regardless of the character set used.
>

Do you have a link for that?


> > case 0...9 is not valid because 0. and .9 are parsed as
> floating-point-literals, with one . between.
>
> 0...9 is parsed as one pp-number, rather than three tokens.
>

Hmm, I was under the impression that the pp-tokens are broken up into one
or more tokens, so that's what you would eventually get those three tokens
out of it.