On Thu, Sep 06, 2007 at 05:06:52PM +0200, David Kastrup wrote:
> > If an object that has automatic storage duration is not initialized
> > explicitly, its value is indeterminate. If an object that has static
> > storage duration is not initialized explicitly, then:
> >
> > -- if it has pointer type, it is initialized to a null pointer;
>
> That's actually a new one to me. I don't think that it has been
> always the case in ANSI C.
I don't have the C89 standard, so it's hard to be authoritative.
However, according to TCOR1 to the C89 standard, the original text of
6.5.7 contained:
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.
and was changed to:
If an object that has static 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 zero;
- if it is an aggregate, every member is initialized (recursively)
according to these rules;
- if it is a union, the first named member is initialized
(recursively) according to these rules.
But for the case of pointer initializations, both have the same effect.
So I think it has always been the case. Pre-ANSI, who knows. :)
You can find TCOR1 here:
http://www.open-std.org/jtc1/sc22/wg14/www/docs/tc1.htm
And now I must go get some real work done instead of snooping through
standards. :)
-Peff
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