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| From | Stephen Sprunk <stephen@sprunk.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Do variables need to be initialized? |
| Date | 2015-06-10 14:33 -0500 |
| Organization | A noiseless patient Spider |
| Message-ID | <mla3bt$hs6$1@dont-email.me> (permalink) |
| References | (3 earlier) <6711371c-5e7c-4af2-a629-6d701827a2a5@googlegroups.com> <mkshk3$9jt$1@dont-email.me> <mkslqf$srg$1@dont-email.me> <mkv615$n3r$1@dont-email.me> <mkvcv9$jji$1@dont-email.me> |
On 06-Jun-15 13:09, Bartc wrote:
> On 06/06/2015 17:11, Stephen Sprunk wrote:
>> On 05-Jun-15 12:22, Bartc wrote:
>>> That seems to be still the case, in that functions need to be
>>> declared before use (or at least, will cause problems if they're
>>> not).
>>
>> That's because you need to know the argument and return types to
>> properly generate the code to call the function.
>
> That can't have been the actual reason for decades. It's unlikely
> that final code will be generated for a function before the rest of
> the file has been scanned.
Probably not these days, but the way C is defined, a compiler _could_
work line by line and conform, even if none of them actually still do
(or ever did) so. That may seem silly, but it is what it is.
> But C compilers still seem happy to generate code for a non-existent
> function that they've not had sight of at all; gcc compiles this with
> no problem:
>
> int main(void) {
> anyfunction(10,20,30.9);
> }
That's because there was a specific rule in the Standard on what to do
when code calls a function that hasn't been declared yet.
That was eventually recognized as a Bad Idea(tm) and removed in later
versions, but some compilers still do it anyway, or default to an older
version of C where it was still allowed. Presumably, they wouldn't do
that unless it were necessary to avoid breaking old code.
C still allows function declarations with unspecified arguments, even
though that has also been known to be Bad Idea(tm) for just as long.
S
--
Stephen Sprunk "God does not play dice." --Albert Einstein
CCIE #3723 "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking
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Do variables need to be initialized? fl <rxjwg98@gmail.com> - 2015-06-01 16:48 -0700
Re: Do variables need to be initialized? Richard Heathfield <rjh@cpax.org.uk> - 2015-06-02 00:55 +0100
Re: Do variables need to be initialized? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-06-01 18:22 -0600
Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-06-02 08:05 -0700
Re: Do variables need to be initialized? Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 08:07 -0700
Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-07-11 16:47 -0700
Re: Do variables need to be initialized? Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-15 07:42 -0700
Re: Do variables need to be initialized? Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 08:03 -0700
Re: Do variables need to be initialized? David Brown <david.brown@hesbynett.no> - 2015-06-02 09:15 +0200
Re: Do variables need to be initialized? Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 08:09 -0700
Re: Do variables need to be initialized? David Kleinecke <dkleinecke@gmail.com> - 2015-06-03 09:30 -0700
Re: Do variables need to be initialized? gwowen <gwowen@gmail.com> - 2015-06-03 09:41 -0700
Re: Do variables need to be initialized? David Kleinecke <dkleinecke@gmail.com> - 2015-06-04 10:17 -0700
Re: Do variables need to be initialized? Stephen Sprunk <stephen@sprunk.org> - 2015-06-05 11:10 -0500
Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-05 18:22 +0100
Re: Do variables need to be initialized? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-06-05 20:54 -0600
Re: Do variables need to be initialized? Ian Collins <ian-news@hotmail.com> - 2015-06-06 15:49 +1200
Re: Do variables need to be initialized? Dr Nick <nospam-4@temporary-address.org.uk> - 2015-06-06 08:42 +0100
Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-06-06 13:11 -0700
Re: Do variables need to be initialized? Dr Nick <nospam-4@temporary-address.org.uk> - 2015-06-07 16:58 +0100
Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-06 11:01 +0100
Re: Do variables need to be initialized? Ian Collins <ian-news@hotmail.com> - 2015-06-07 09:07 +1200
Re: Do variables need to be initialized? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-06-06 15:06 -0600
Re: Do variables need to be initialized? gwowen <gwowen@gmail.com> - 2015-06-08 05:39 -0700
Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-08 14:10 +0100
Re: Do variables need to be initialized? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-08 14:21 +0100
Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-08 14:34 +0100
Re: Do variables need to be initialized? David Brown <david.brown@hesbynett.no> - 2015-06-08 16:51 +0200
Re: Do variables need to be initialized? Richard Heathfield <rjh@cpax.org.uk> - 2015-06-08 16:15 +0100
Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-08 17:31 +0100
Re: Do variables need to be initialized? Ian Collins <ian-news@hotmail.com> - 2015-06-09 08:06 +1200
Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-08 22:58 +0100
Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-06-08 08:27 -0700
Re: Do variables need to be initialized? gwowen <gwowen@gmail.com> - 2015-06-08 08:01 -0700
Re: Do variables need to be initialized? Stephen Sprunk <stephen@sprunk.org> - 2015-06-06 11:11 -0500
Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-06 19:09 +0100
Re: Do variables need to be initialized? Robert Wessel <robertwessel2@yahoo.com> - 2015-06-06 13:57 -0500
Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-06-06 13:52 -0700
Re: Do variables need to be initialized? James Kuyper <jameskuyper@verizon.net> - 2015-06-06 20:57 -0400
Re: Do variables need to be initialized? Stephen Sprunk <stephen@sprunk.org> - 2015-06-10 14:33 -0500
Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-06-05 10:56 -0700
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