Hi Keith,
On 02/26/2016 08:52 PM, Keith Thompson wrote:
> On Fri, Feb 26, 2016 at 7:46 AM, Michael Kerrisk (man-pages)
> <mtk.manpages@xxxxxxxxx> wrote:
>> On 02/24/2016 10:26 AM, Martin Gebert wrote:
>>> In the example section of the page the following snippet is given:
>>>
>>> --8><--
>>> void
>>> myfunc3(void)
>>> {
>>> int j, nptrs;
>>> #define SIZE 100
>>> void *buffer[100];
>>> char **strings;
>>>
>>> nptrs = backtrace(buffer, SIZE);
>>> --><8--
>>>
>>> Problems:
>>>
>>> 1. "#define SIZE 100" is not indented correctly.
>>> 2. SIZE should also be used for the buffer array size.
>>
>> Thanks, Martin. Fixed as below.
>>
>> Cheers,
>>
>> Michael
>>
>> diff --git a/man3/backtrace.3 b/man3/backtrace.3
>> index afca93d..064b970 100644
>> --- a/man3/backtrace.3
>> +++ b/man3/backtrace.3
>> @@ -215,8 +215,8 @@ void
>> myfunc3(void)
>> {
>> int j, nptrs;
>> -#define SIZE 100
>> - void *buffer[100];
>> + const int SIZE = 100;
>> + void *buffer[SIZE];
>> char **strings;
>>
>> nptrs = backtrace(buffer, SIZE);
>
> I suggest leaving it as it was, apart from using SIZE in the definition
> of buffer.
>
> It's common for preprocessor directives to be left-justified rather
> than aligned with the surrounding code. (They mostly appear at file
> scope, so it's not usually an issue.) It's perfectly valid to indent
> the #define, but it's a bit misleading, since it implies that SIZE has
> a scope (it doesn't, it's visible to the end of the translation unit).
>
> With the "const int" declaration, buffer becomes a VLA (variable
> length array). VLAs don't exist in C90, do exist in C99, and are
> optional in C11.
Ahhh -- I was not aware of the C11 detail.
> The code won't compile with "gcc -pedantic-errors".
Which gcc versions do that? I do not see such an error from gcc 5.3.
Cheers,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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