Hi Ho!
Sorry, if I sort of hijack this thread.
On Wed, 2009-04-29 at 15:43 +0000, Joseph S. Myers wrote:
> > > "int i;" is not the same as "extern int i;".
> >
> > Sorry for my ignorance but I have been reading and searching for the
> > answer and I cannot tell what is the difference between "int i = 1"
> > and "extern int i = 1" at file-scope in C.
>
> I did not say those were different, I said the uninitialized case was
> different, so "extern is implicit if missing" is not a general C rule.
I think the difference between "int i;" and "extern int i;" at
file-scope in C is that "int i;" will only be treated as a definition if
it is not defined in another place in the same file/TU. IOW, its linkage
is internal within the TU itself. But, "extern int i" is definitely
treated as a declaration only that can later be defined either in the
same TU or in another one.
Is that true?
Finally, is there any difference in declaring a non-inline function
prototype with and without "extern" in C? That is, is there any
difference between:
extern int foo (int *bar);
and
int foo (int *bar);
?
I think they are completely identical. Is that correct?
Also, is there any difference in defining a non-inline function with and
without "extern" in C? That is, is there any difference between:
extern int foo (int *bar)
{
return *bar + 5;
}
and
int foo (int *bar)
{
return *bar + 5;
}
?
I think they are also identical. Am I right? Who knows the one with
"extern" can be overridden in another TU defining its own definition
without "extern".
Thank you for your help :-)
> --
> Joseph S. Myers
> jos...@codesourcery.com
--
Best regards,
Eus (FSF member #4445)
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