the same id in the same scope refers to different objects
Mason
slash.tmp@free.fr
Mon Sep 4 13:24:00 GMT 2017
On 04/09/2017 15:17, Andrew Makhorin wrote:
> On Mon, 2017-09-04 at 10:33 +0100, Jonathan Wakely wrote:
>> On 3 September 2017 at 11:43, Andrew Makhorin wrote:
>>> Why x used to initialize y identifies not the same object as x used in
>>> printf though x is the same identifier within the same block scope?
>>
>> Because that's how scope and visibility works in the C programming
>> language. A name is only in scope after it has been declared. Get a
>> good book on C programming.
>
> Thank you for your reply.
>
> I think the ISO C Standard is a good book. The subsection 6.2.1
> "Scopes of identifiers" says:
>
> Different entities designated by the same identifier either have
> different scopes, or are in different name spaces.
> [...]
> Two identifiers have the same scope if and only if their scopes
> terminate at the same point.
>
> In my example program x used in printf has block scope which overlaps
> the file scope where other x is declared. Thus, the behavior of my
> example program is undefined, because x is used to initialize y before
> it is assigned an initial value (this is similar to the case when a
> goto jumps into a block bypassing possible initialization of variables
> declared within that block).
In my opinion, your analysis is incorrect.
I suggest asking in the comp.lang.c Usenet newsgroup.
You will find experts who know the standard inside-out.
Regards.
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