Re: uninitialized++;

Article View: comp.std.c

Article #2930

#2930

From: Mike Ball
Date: Wed, 30 Dec 1992 17:21

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1241 bytes

diamond@jit533.jit.dec.com (Norman Diamond) writes:

>In article <9236508.13290@mulga.cs.mu.OZ.AU> fjh@munta.cs.mu.OZ.AU (Fergus James HENDERSON) writes:
>>hbf@gandalf.uio.no (Hallvard B Furuseth) writes:
>>>Can this fail  - on some machine?  - in ANSI?
>  main () { int uninitialized; uninitialized += 0; return 0; }
>I think this one is not allowed to fail.

To quote from the standard., section 1.6
"Undefined behavior - behavior, upon use of a nonportable or erroneous
program construct, or erroneous data, or of indeterminately valued objects,
for which the standard imposes no requirements."

And 3.5.7
"If an object that has automatic storage duration is not initialized
explicitly, its value is indeterminate."

Sounds like any use of the value, even adding 0, is undefined.
-- 
Michael S. Ball (mike@taumet.com)
TauMetric Corporation

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Message-ID: <1992Dec30.172142.22789@taumet.com>

Path: arc1-ca.pugleaf.net!sparky!uunet!taumet!mike

References: <HBF.92Dec29211517@gandalf.uio.no> <9236508.13290@mulga.cs.mu.OZ.AU> <C02DDv.2Kw@jrd.dec.com>

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Newsgroups: comp.std.c,comp.lang.c
Path: arc1-ca.pugleaf.net!sparky!uunet!taumet!mike
From: mike@taumet.com (Mike Ball)
Subject: Re: uninitialized++;
Message-ID: <1992Dec30.172142.22789@taumet.com>
Organization: TauMetric Corporation
References: <HBF.92Dec29211517@gandalf.uio.no> <9236508.13290@mulga.cs.mu.OZ.AU> <C02DDv.2Kw@jrd.dec.com>
Date: Wed, 30 Dec 1992 17:21:42 GMT
Lines: 21

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