Re: compute ISBN-10, char-to-int?

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Sat, 07 Sep 2019 13:13:45 -0400
> 
> I think the main threat could come from a charset where digits appear
> multiple times (e.g. some kind of iso-2022 system where some of the
> sub-charsets also include digits), in which case (+ n ?0) would still
> work but (- c ?0) could occasionally fail.  But, I don't know of such
> a charset either.

All true, but not really relevant to the issue at hand, because in
Emacs characters are always Unicode codepoints.