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Re: Second draft, "Safe arrays and pointers for C"

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On 9/3/2012 11:39 AM, Ike Naar wrote:
> On 2012-09-03, BGB <cr88192@hotmail.com> wrote:
>> On 9/2/2012 3:20 PM, Hans-Bernhard Br?ker wrote:
>>> On 01.09.2012 02:26, John Nagle wrote:
>>>
>>>>      Not really.  The main use case for unions is for data read
>>>> in from an external source, often a network.
>>>
>>> No, it's not, because the vast majority of usages of unions for that
>>> purpose would automatically cause undefined behaviour.
>>>
>>
>> yeah, and also most cases I have seen unions used for have little to do
>> with network data.
>>
>>
>>>>      Tightening down the screws further on that would alienate too many C
>>>> programmers.  Consider the common idiom
>>>>
>>>>      const char* msg[] =
>>>>      {"First message", "second message", "third message", 0 }
>>>
>>
>> (ironically, the above will probably only work without issue in C++, and
>> in C will usually generate a message something like "warning: int to
>> pointer conversion without a cast" or similar... this means the array
>> needs to be terminated with either NULL or "((void *)0)" or "((char
>> *)0)" or similar to avoid the compiler complaining about it).
>
> In C, 0 is perfectly fine as a char* (it's a null pointer constant).
> Have you really seen warnings for this?
>

I remembered seeing them in the past.

testing again, I don't seem to be getting a warning with either MSVC or 
GCC, so maybe I was wrong or misremembering?... (or it was a 
compiler-version specific issue with a past version of GCC or similar?...)

at the moment, there is no issue with a constant value of 0, but if the 
value is anything other than 0, then there is a message.


fair enough, 0 seems to work...

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Second draft, "Safe arrays and pointers for C" John Nagle <nagle@animats.com> - 2012-08-30 12:48 -0700
  Re: Second draft, "Safe arrays and pointers for C" pacman@kosh.dhis.org (Alan Curry) - 2012-08-31 22:17 +0000
    Re: Second draft, "Safe arrays and pointers for C" John Nagle <nagle@animats.com> - 2012-08-31 17:26 -0700
      Re: Second draft, "Safe arrays and pointers for C" Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2012-09-02 22:20 +0200
        Re: Second draft, "Safe arrays and pointers for C" BGB <cr88192@hotmail.com> - 2012-09-03 10:55 -0500
          Re: Second draft, "Safe arrays and pointers for C" Ike Naar <ike@iceland.freeshell.org> - 2012-09-03 16:39 +0000
            Re: Second draft, "Safe arrays and pointers for C" BGB <cr88192@hotmail.com> - 2012-09-03 13:18 -0500
  Re: Second draft, "Safe arrays and pointers for C" Jens Gustedt <jens.gustedt@loria.fr> - 2012-09-02 10:52 +0200
  Re: Second draft, "Safe arrays and pointers for C" Per <per.mathisen@gmail.com> - 2012-09-28 06:49 -0700
    Re: Second draft, "Safe arrays and pointers for C" John Nagle <nagle@animats.com> - 2012-09-28 11:36 -0700
      Re: Second draft, "Safe arrays and pointers for C" Per <per.mathisen@gmail.com> - 2012-10-01 09:38 -0700
        Re: Second draft, "Safe arrays and pointers for C" John Nagle <nagle@animats.com> - 2012-10-01 11:38 -0700
      Re: Second draft, "Safe arrays and pointers for C" Shao Miller <sha0.miller@gmail.com> - 2012-12-17 09:11 -0500
        Re: Second draft, "Safe arrays and pointers for C" Keith Thompson <kst-u@mib.org> - 2012-12-17 10:18 -0800
          Re: Second draft, "Safe arrays and pointers for C" Shao Miller <sha0.miller@gmail.com> - 2012-12-17 18:24 -0500
            Re: Second draft, "Safe arrays and pointers for C" Shao Miller <sha0.miller@gmail.com> - 2012-12-17 18:32 -0500
            Re: Second draft, "Safe arrays and pointers for C" Keith Thompson <kst-u@mib.org> - 2012-12-17 15:44 -0800

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