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Groups > comp.arch.embedded > #26283

Re: Dimension of a matrix

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.arch.embedded
Subject Re: Dimension of a matrix
Date 2017-03-26 17:32 +0200
Organization A noiseless patient Spider
Message-ID <ob8mok$fch$2@dont-email.me> (permalink)
References <rtKdndPJ5_gVyknFnZ2dnUU7-UfNnZ2d@giganews.com> <ob2kn7$vd$3@dont-email.me> <ob6bi3$a7o$1@dont-email.me> <ejnti4FbilfU1@mid.dfncis.de> <ob6irp$nv$4@dont-email.me>

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On 25/03/17 21:17, Les Cargill wrote:
> Hans-Bernhard Bröker wrote:
>> Am 25.03.2017 um 19:12 schrieb Les Cargill:
>>> David Brown wrote:
>>
>>> I could not tell you which versions of which compilers support this,
>>> but in some toolchains, it's possible to specify the size of an array
>>> being passed - void p(char x[256])... .
>>
>> All C compilers are actually required to allow you to pass a size like
>> that.  It doesn't have any effect whatsoever, though.  Any number you
>> put between those [] is really just decoration.  These 4 function
>> declarations are totally equivalent:
>>
>>     void p(char x[256]);
>>     void p(char x[7]);
>>     void p(char x[]);
>>     void p(char *x);
>>
>>
>
> I recall (vaguely) code where sizeof(x) would return 256, but it's a
> hazy memory. I don't remember the toolchain; probably latter day MS
> VS stuff.

That would be a broken compiler.

>
> And even if it's just decoration, it preserves the size of the array out
> of band.
>

Specifying the size here is just a comment.  And it is a dangerous 
comment, because it /looks/ like it might be something that the compiler 
will check, or that lets you use "sizeof" in the manner you describe - 
but it will not.  In all the cases above, "x" is a pointer to char - 
/not/ an array.

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Thread

Dimension of a matrix Tim Wescott <seemywebsite@myfooter.really> - 2017-03-23 18:17 -0500
  Re: Dimension of a matrix Paul Rubin <no.email@nospam.invalid> - 2017-03-23 23:21 -0700
    Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-24 09:18 +0100
      Type-safety and C++, was: Re: Dimension of a matrix Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2017-03-24 18:24 +0000
        Re: Type-safety and C++, was: Re: Dimension of a matrix Tim Wescott <tim@seemywebsite.com> - 2017-03-24 19:32 -0500
          Re: Type-safety and C++, was: Re: Dimension of a matrix Stefan Reuther <stefan.news@arcor.de> - 2017-03-25 09:59 +0100
          Re: Type-safety and C++, was: Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-25 13:08 -0500
        Re: Type-safety and C++, was: Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-25 01:57 +0100
          Re: Type-safety and C++, was: Re: Dimension of a matrix Clifford Heath <no.spam@please.net> - 2017-03-25 18:34 +1100
            Re: Type-safety and C++, was: Re: Dimension of a matrix Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2017-03-26 23:53 +0000
              Re: Type-safety and C++, was: Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-27 09:51 +0200
                Re: Type-safety and C++, was: Re: Dimension of a matrix Clifford Heath <no.spam@please.net> - 2017-03-27 20:19 +1100
                Re: Type-safety and C++, was: Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-27 12:17 +0200
          Re: Type-safety and C++, was: Re: Dimension of a matrix Paul Rubin <no.email@nospam.invalid> - 2017-03-25 09:20 -0700
        Re: Type-safety and C++, was: Re: Dimension of a matrix George Neuner <gneuner2@comcast.net> - 2017-03-24 23:14 -0400
          Re: Type-safety and C++, was: Re: Dimension of a matrix Tim Wescott <tim@seemywebsite.com> - 2017-03-25 11:07 -0500
            Re: Type-safety and C++, was: Re: Dimension of a matrix George Neuner <gneuner2@comcast.net> - 2017-03-26 05:45 -0400
              Re: Type-safety and C++, was: Re: Dimension of a matrix Wouter van Ooijen <wouter@voti.nl> - 2017-03-26 13:14 +0200
                Re: Type-safety and C++, was: Re: Dimension of a matrix Paul Rubin <no.email@nospam.invalid> - 2017-03-26 11:08 -0700
                Re: Type-safety and C++, was: Re: Dimension of a matrix Wouter van Ooijen <wouter@voti.nl> - 2017-03-26 20:24 +0200
              Re: Type-safety and C++, was: Re: Dimension of a matrix Tim Wescott <tim@seemywebsite.com> - 2017-03-26 15:16 -0500
                Re: Type-safety and C++, was: Re: Dimension of a matrix Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2017-03-27 00:09 +0000
                Re: Type-safety and C++, was: Re: Dimension of a matrix Tim Wescott <seemywebsite@myfooter.really> - 2017-03-26 19:43 -0500
                Re: Type-safety and C++, was: Re: Dimension of a matrix Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-27 16:57 +0100
                Re: Type-safety and C++, was: Re: Dimension of a matrix Tim Wescott <tim@seemywebsite.com> - 2017-03-27 11:53 -0500
                Re: Type-safety and C++, was: Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-27 22:04 +0200
                Re: Type-safety and C++, was: Re: Dimension of a matrix Tim Wescott <seemywebsite@myfooter.really> - 2017-03-27 18:32 -0500
                Re: Type-safety and C++, was: Re: Dimension of a matrix Clifford Heath <no.spam@please.net> - 2017-03-28 11:03 +1100
                Re: Type-safety and C++, was: Re: Dimension of a matrix Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-27 22:07 +0100
                Re: Type-safety and C++, was: Re: Dimension of a matrix Paul Rubin <no.email@nospam.invalid> - 2017-03-27 23:42 -0700
                Re: Type-safety and C++, was: Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-28 09:22 +0200
                Re: Type-safety and C++, was: Re: Dimension of a matrix Paul Rubin <no.email@nospam.invalid> - 2017-03-28 00:42 -0700
                Re: Type-safety and C++, was: Re: Dimension of a matrix Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-03-28 09:07 +0100
                Re: Type-safety and C++, was: Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-28 19:34 -0500
                Re: Type-safety and C++, was: Re: Dimension of a matrix Tim Wescott <tim@seemywebsite.com> - 2017-03-29 11:39 -0500
                Re: Type-safety and C++, was: Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-28 19:29 -0500
                Re: Type-safety and C++, was: Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-29 10:31 +0200
                Re: Type-safety and C++, was: Re: Dimension of a matrix Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2017-03-30 00:23 +0000
                Re: Type-safety and C++, was: Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-29 19:31 -0500
                Re: Type-safety and C++, was: Re: Dimension of a matrix Phil Martel <pomartel@comcast.net> - 2017-03-30 11:51 -0400
                Re: Type-safety and C++, was: Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-30 19:16 -0500
                Re: Type-safety and C++, was: Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-31 09:21 +0200
                Re: Type-safety and C++, was: Re: Dimension of a matrix Tim Wescott <seemywebsite@myfooter.really> - 2017-03-28 14:19 -0500
    Re: Dimension of a matrix Tim Wescott <tim@seemywebsite.com> - 2017-03-24 11:05 -0500
      Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-24 17:33 +0100
        Re: Dimension of a matrix Tim Wescott <tim@seemywebsite.com> - 2017-03-24 12:09 -0500
      Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-25 13:09 -0500
    Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-25 13:05 -0500
  Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-24 09:20 +0100
    Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-25 13:12 -0500
      Re: Dimension of a matrix Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2017-03-25 20:08 +0100
        Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-25 15:17 -0500
          Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-26 17:32 +0200
            Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-26 11:55 -0500
              Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-26 21:23 +0200
                Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-29 19:36 -0500
                Re: Dimension of a matrix Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2017-03-30 00:36 +0000
                Re: Dimension of a matrix Paul Rubin <no.email@nospam.invalid> - 2017-03-29 19:55 -0700
                Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-30 09:49 +0200
                Re: Dimension of a matrix Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2017-03-30 18:07 +0000
                Re: Dimension of a matrix David Brown <david.brown@hesbynett.no> - 2017-03-30 09:47 +0200
  Re: Dimension of a matrix Wouter van Ooijen <wouter@voti.nl> - 2017-03-25 19:08 +0100
    Re: Dimension of a matrix Les Cargill <lcargill99@comcast.com> - 2017-03-25 15:21 -0500
      Re: Dimension of a matrix Wouter van Ooijen <wouter@voti.nl> - 2017-03-26 14:43 +0200

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