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Message-ID: <1429302857.14591.1.camel@inria.fr>
Date: Fri, 17 Apr 2015 22:34:17 +0200
From: Jens Gustedt <jens.gustedt@...ia.fr>
To: musl@...ts.openwall.com
Subject: Re: Explicit casts in ctype.h suppress compiler warnings
Am Freitag, den 17.04.2015, 20:35 +0200 schrieb Szabolcs Nagy:
> #define isdigit(a) (((0?1U:(a))-'0') < 10)
>
> which works when the conversion rank of a is <= unsigned
but not if it has conversion rank larger then unsigned and the result
of the substraction has a negative result. So what you think of
#define isdigit(a) (((0?1ULL:(a))-'0') < 10ULL)
This ensures that the type of the left is always ullong, so the
substraction overflows to something big if a is not a digit.
Jens
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