Date: Wed, 26 Jan 2005 10:08:39 +0000 From: Steven Smith <sos22@cantab.net> To: Giorgos Keramidas <keramida@ceid.upatras.gr> Cc: Steven Smith <sos22@cantab.net> Subject: Re: Dubious #define in include/pwd.h Message-ID: <20050126100839.GA4367@archibold> In-Reply-To: <20050126004033.GA2640@gothmog.gr> References: <20050125214606.GB1113@archibold> <20050126004033.GA2640@gothmog.gr>
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> > I was messing around with sparse, the static checker used sometimes
> > by Linux kernel people, and I (or rather, it) came upon the line
> >
> > #define _PW_VERSION_MASK '0xF0'
> >
> > in /usr/src/include/pwd.h. I can't immediately see any use for this;
> > '\xf0' would probably be more useful.
> If this is used as a mask for 'unsigned char' values, why would it make
> any difference? Aren't they both going to be implicitly converted to
> the right typep anyway?
Well, except for the single quotes around '0xf0'. If you go:
int x = '0xf0';
printf("%d\n", x);
you probably won't get what you expect. If you replace the '0xf0'
with '\xf0' you probably will.
Steven.
--
'Double-entry bookkeeping ....simple to adapt to modern computer
methods by using positive or negative electric charges to signal
whether an account should be debited or credited.'
-- Accounting Theory and Practice, Glautier M.W.E
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