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Re: sysval and doc fixes


From: Gary V. Vaughan
Subject: Re: sysval and doc fixes
Date: Thu, 22 Jun 2006 15:45:37 +0100
User-agent: Thunderbird 1.5.0.2 (X11/20060519)

Hallo Ralf!

Ralf Wildenhues wrote:
> Gary V. Vaughan <gary <at> gnu.org> writes:
>> Eric Blake wrote:
>>>>> static int sysval = 0;
>>> That's redundant.  Uninitialized static variables live in .bss and are
>>> 0-initialized by the C runtime (it is only the heap and uninitialized
>>> local variables that have garbage values).
>> That is implementation defined IMHO.
> 
> No.  This has nothing to do with ELF section, but is required by C.
> C89, 3.1.2.4:
> |    An object declared with external or internal linkage, or with the
> | storage-class specifier static has static storage duration.  For such
> | an object, storage is reserved and its stored value is initialized
> | only once, prior to program startup.
> 
> and 3.5.7:
> |    If an object that has static storage duration is not initialized
> | explicitly, it is initialized implicitly as if every member that has
> | arithmetic type were assigned 0 and every member that has pointer type
> | were assigned a null pointer constant.  If an object that has
> | automatic storage duration is not initialized explicitly, its value is
> | indeterminate./65/

Okay, thanks.  I didn't know that.

Cheers,
        Gary.
-- 
Gary V. Vaughan      ())_.  address@hidden,gnu.org}
Research Scientist   ( '/   http://blog.azazil.net
GNU Hacker           / )=   http://trac.azazil.net/projects/libtool
Technical Author   `(_~)_   http://sources.redhat.com/autobook

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