snprintf() with g++ -std=c++98: error: 'snprintf' was not declared in this scope

Ryan Johnson ryan.johnson@cs.utoronto.ca
Wed Apr 4 17:50:00 GMT 2012


On 04/04/2012 11:18 AM, Corinna Vinschen wrote:
> On Apr  4 16:54, Denis Excoffier wrote:
>> On Wed, Apr 04, 2012 at 10:02:24AM -0400, Ryan Johnson wrote:
>>>> On 04/04/2012 9:32 AM, Denis Excoffier wrote:
>>>>> Hello,
>>>>>
>>>>> It could be that snprintf() is not properly declared in<stdio.h>.
>>>> According to [1], it's not officially part of c++98 (???). Try
>>>> gnu++98 instead. As for why it's not in c++0x, there's a problem
>>>> with the macros being defined [2] that AFAIK remains unresolved;
>>>> again the workaround is gnu++0x.
>>>>
>>>> [1] http://cygwin.com/ml/cygwin/2010-01/msg00791.html
>>>> [2] http://cygwin.com/ml/cygwin/2011-08/msg00311.html
>>>>
>> Oh, i should have found these, at least the first one... For c++0x,
>> couldn't this be addressed now? As a start, i can (humbly) propose:
>>
>> --- stdio.h	2012-04-04 14:50:32.000000000 +0159
>> +++ stdio.h++	2012-04-04 16:38:21.049273700 +0159
>> @@ -237,7 +237,7 @@
>>   off_t	_EXFUN(ftello, ( FILE *));
>>   #endif
>>   #endif
>> -#if !defined(__STRICT_ANSI__) || (__STDC_VERSION__>= 199901L)
>> +#if !defined(__STRICT_ANSI__) || (__STDC_VERSION__>= 199901L) || (__cplusplus>= 201103L)
> How is that supposed to work?
>
>    $ gcc -xc++ -std=c++98 -dM -E -<  /dev/null | grep cplus
>    #define __cplusplus 1
>
>    $ gcc -xc++ -std=c++0x -dM -E -<  /dev/null | grep cplus
>    #define __cplusplus 1
>
> Actually I'm wondering if that's not a bug in gcc:
>
>    $ gcc -xc -std=c89 -dM -E -<  /dev/null | grep STDC
>    #define __STDC_HOSTED__ 1
>    #define __STDC__ 1
>
>    $ gcc -xc -std=c99 -dM -E -<  /dev/null | grep STDC
>    #define __STDC_HOSTED__ 1
>    #define __STDC_VERSION__ 199901L
>    #define __GNUC_STDC_INLINE__ 1
>    #define __STDC__ 1
>
>    [~]$ gcc -xc++ -std=c++98 -dM -E -<  /dev/null | grep STDC
>    #define __STDC_HOSTED__ 1
>    #define __STDC__ 1
>    [~]$ gcc -xc++ -std=c++0x -dM -E -<  /dev/null | grep STDC
>    #define __STDC_HOSTED__ 1
>    #define __STDC__ 1
>
> Shouldn't -std=c++0x include the definitions for -std=c99, namely
>
>    #define __STDC_VERSION__ 199901L
>
> ???
I figured it was a gcc bug from the start, but I don't know enough about 
the arcane art of juggling all possible combinations of __STDC__, 
__ANSI__, etc. and wouldn't know the first thing about a fix. I just 
live with -std=gnu++$WHATEVER for now.

Ryan


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