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Is gcc compliant with the C++ standards


 
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# 1  
Old 07-29-2009
Is gcc compliant with the C++ standards

Hello Friends,

I am a newbie and have started using different compilers and tools to make myself familiar with their workings. I wanted to know that how compliant is gcc with the C++ standards. It is pretty obvious that no compiler is close to being completely compliant, but if there are some things which are not according to the ANSI/ISO standard; what are they in gcc?

I will be very grateful if someone who is an expert user of gcc can answer this doubt of mine?

Regards.
# 2  
Old 07-30-2009
http://gcc.gnu.org/onlinedocs/gcc-4.4.1/gcc.pdf
There is a section on ANSI support. 4.4.1 does provide full ANSI support, except in specialty environments like embedded Linux or ARM, or in really old releases of gcc.

For C++ issues mostly boil down to extensions and implementation defined behaviors (semantics). You have read a lot, there is no way to shortcut that.
# 3  
Old 07-30-2009
Quote:
Originally Posted by hthapar
Hello Friends,

I am a newbie and have started using different compilers and tools to make myself familiar with their workings. I wanted to know that how compliant is gcc with the C++ standards. It is pretty obvious that no compiler is close to being completely compliant, but if there are some things which are not according to the ANSI/ISO standard; what are they in gcc?

I will be very grateful if someone who is an expert user of gcc can answer this doubt of mine?

Regards.
gcc can be told comply with standards, lots of them. Pick your favorite:
Code:
$ man gcc

GCC(1)                                GNU                               GCC(1)



NAME
       gcc - GNU project C and C++ compiler

SYNOPSIS
       gcc [-c|-S|-E] [-std=standard]
           [-g] [-pg] [-Olevel]
           [-Wwarn...] [-pedantic]
           [-Idir...] [-Ldir...]
           [-Dmacro[=defn]...] [-Umacro]
           [-foption...] [-mmachine-option...]
           [-o outfile] infile...

       Only the most useful options are listed here; see below for the remain-
       der.  g++ accepts mostly the same options as gcc.

...

       -std=
           Determine the language standard.  This option is currently only
           supported when compiling C or C++.  A value for this option must be
           provided; possible values are

           c89
           iso9899:1990
               ISO C90 (same as -ansi).

           iso9899:199409
               ISO C90 as modified in amendment 1.

           c99
           c9x
           iso9899:1999
           iso9899:199x
               ISO C99.  Note that this standard is not yet fully supported;
               see <http://gcc.gnu.org/gcc-4.1/c99status.html> for more infor-
               mation.  The names c9x and iso9899:199x are deprecated.

           gnu89
               Default, ISO C90 plus GNU extensions (including some C99 fea-
               tures).

           gnu99
           gnu9x
               ISO C99 plus GNU extensions.  When ISO C99 is fully implemented
               in GCC, this will become the default.  The name gnu9x is depre-
               cated.

           c++98
               The 1998 ISO C++ standard plus amendments.

           gnu++98
               The same as -std=c++98 plus GNU extensions.  This is the
               default for C++ code.

           Even when this option is not specified, you can still use some of
           the features of newer standards in so far as they do not conflict
           with previous C standards.  For example, you may use "__restrict__"
           even when -std=c99 is not specified.

           The -std options specifying some version of ISO C have the same
           effects as -ansi, except that features that were not in ISO C90 but
           are in the specified version (for example, // comments and the
           "inline" keyword in ISO C99) are not disabled.

gcc also has lots of language extensions, but you don't need to use them.
# 4  
Old 07-30-2009
Quote:
It is pretty obvious that no compiler is close to being completely compliant
I am curious how you came to that conclusion.
# 5  
Old 07-30-2009
I have been using VS2005 for some time and also did a lot of reading on other compilers.
Well I observed that, each platform is providing extensions and libraries based only for their system/platform and at the same time even if you are able to port these platform-specific libraries to other compilers, still the compliance issue is lost to some extent.
Maybe I was wrong in generalizing it, but it was just an opinion.
# 6  
Old 07-30-2009
Moving an application from Microsoft C++ to another C++ environment is nearly always challanging. Build failures usually comes down to (1) the silent non-standard compiler extensions that Microsoft supports by default (for example lvalue casts, zero length structure members) and (2) the fact that common C++ libraries have yet to be fully standardized. It is rarely the core C++ compiler itself.
# 7  
Old 07-30-2009
Very true

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