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[Frama-c-discuss] Jessie - static variable

On Tue, Feb 19, 2013 at 9:09 AM, Claude Marche <Claude.Marche at inria.fr> wrote:
> Notice that it seems that your code relies on the fact that static variables
> are initialised to 0. I'm not sure it is guaranteed by the C standard.

>From the C11 draft standard of 12 April 2011, Section 6.7.9
(Initialization), paragraph 10:

If an object that has automatic storage duration is not initialized
explicitly, its value is
indeterminate. If an object that has static or thread storage duration
is not initialized
explicitly, then:
? if it has pointer type, it is initialized to a null pointer;
? if it has arithmetic type, it is initialized to (positive or unsigned) zero;
? if it is an aggregate, every member is initialized (recursively)
according to these rules,
and any padding is initialized to zero bits;
? if it is a union, the first named member is initialized
(recursively) according to these
rules, and any padding is initialized to zero bits;

>From the draft C89 standard (see
http://flash-gordon.me.uk/ansi.c.txt), Section 3.5.7 (Initialization),
subsection "Semantics":

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.

Regards,
--
Jerry James
http://www.jamezone.org/