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From: Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
Newsgroups: comp.lang.c,comp.os.msdos.djgpp
Subject: Re: Environment Variables
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Date: 6 Aug 2004 12:44:34 GMT
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[F'up2 c.l.c, because the ball is safely back in their playing field.]

In comp.os.msdos.djgpp CBFalconer <cbfalconer AT yahoo DOT com> wrote:

> I agree with you, provided you use -ansi -pedantic.  

You don't need -pedantic in this case.  What you need is the effect of
-ansi turning off all extensions present in the compiler's runtime
library, compared to the C standard.  In other words, you need a clean
namespace for the above program to reliably print zero, and that's
what -ansi is meant to give you.

On a more relaxed note, you can ask gcc to warn you in situations like
this, while still keeping the full functionality of the standard libc
intact, by using the -fno-common option.  In terms of the standard:
-fno-common turns off the usual Unix linkers' extension of allowing
tentative definitions to be resolved across the entire program, not
just individual translation units.

This problem is actually a comp.lang.c FAQ, and addressed in the C
FAQ.  Usually it happens with the name 'index', which exists in Unix
libc, is not an ANSI/ISO standard C library function, but is *very*
tempting to use as the name of some object in your own source code,
until you run into this the first time.  Go figure.

-- 
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.