printf official specs or docs, ISO C99, and C++
I found https://svn.boost.org/trac10/ticket/10541 today and my guess is Boost.Format hasn't been updated to support the ISO C99 extensions, or the Microsoft type formats. Before any work is done on this, I'm looking for any official C++ documentation related to printf support requirements. For example the compatibility section in http://www.cplusplus.com/reference/cstdio/printf/ indicates certain language levels have requirements. Thanks, Jim
On 10/12/17 21:26, James E. King, III via Boost wrote:
I found https://svn.boost.org/trac10/ticket/10541 today and my guess is Boost.Format hasn't been updated to support the ISO C99 extensions, or the Microsoft type formats. Before any work is done on this, I'm looking for any official C++ documentation related to printf support requirements. For example the compatibility section in http://www.cplusplus.com/reference/cstdio/printf/ indicates certain language levels have requirements.
The C++ standard simply refers to the C standard (see [cstdio.syn]), so you should look there for the primary specification. I think there are also a few POSIX extensions, which are widely supported and probably worth supporting as well. Microsoft extensions like those mentioned in the ticket are probably less useful because they are not present outside MSVC. Supporting those extentions encourages non-portable code. Regardless of the set of features you choose to support, IMO it should be the same regardless of the compiler/platform/C++ version being targeted.
On Thu, Oct 12, 2017 at 5:23 PM, Andrey Semashev via Boost < boost@lists.boost.org> wrote:
On 10/12/17 21:26, James E. King, III via Boost wrote:
I found https://svn.boost.org/trac10/ticket/10541 today and my guess is Boost.Format hasn't been updated to support the ISO C99 extensions, or the Microsoft type formats. Before any work is done on this, I'm looking for any official C++ documentation related to printf support requirements. For example the compatibility section in http://www.cplusplus.com/reference/cstdio/printf/ indicates certain language levels have requirements.
The C++ standard simply refers to the C standard (see [cstdio.syn]), so you should look there for the primary specification. I think there are also a few POSIX extensions, which are widely supported and probably worth supporting as well. Microsoft extensions like those mentioned in the ticket are probably less useful because they are not present outside MSVC. Supporting those extentions encourages non-portable code.
Regardless of the set of features you choose to support, IMO it should be the same regardless of the compiler/platform/C++ version being targeted.
Perhaps a good place to start looking for discrepancies would be the ISO C11 specification then? http://www.open-std.org/jtc1/sc22/WG14/www/docs/n1570.pdf Specifically sections 7.8.1 and 7.21.6 and 7.29.2. - Jim
On Thu, Oct 12, 2017 at 6:39 PM, James E. King, III via Boost < boost@lists.boost.org> wrote:
Perhaps a good place to start looking for discrepancies would be the ISO C11 specification then? http://www.open-std.org/jtc1/sc22/WG14/www/docs/n1570.pdf Specifically sections 7.8.1 and 7.21.6 and 7.29.2.
If you haven't already done so, you also might want to review Victor Zverovich's standards committee Format proposal. See http://wg21link.p0645 and also his CppCon presentation at https://www.youtube.com/watch?v=ptba_AqFYCM The R0 version got a very favorable reception from the LEWG this summer, so expect an R1 revision in a week or ten days when the committee's Albuquerque pre-meeting mailing becomes available. --Beman
participants (3)
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Andrey Semashev -
Beman Dawes -
James E. King, III