Re: [Boost-bugs] [Boost C++ Libraries] #3634: to_upper / to_lower incorrect for machines with signed chars

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #3634: to_upper / to_lower incorrect for machines with signed chars
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-01-10 18:08:03

#3634: to_upper / to_lower incorrect for machines with signed chars
------------------------------------------------------+---------------------
  Reporter:  Thomas Dorner <td-eclipse@…>             |       Owner:  marshall 
      Type:  Bugs                                     |      Status:  new      
 Milestone:  Boost 1.41.0                             |   Component:  algorithm
   Version:  Boost 1.40.0                             |    Severity:  Problem  
Resolution:                                           |    Keywords:           
------------------------------------------------------+---------------------

Comment (by marshall):

 Replying to [comment:3 pavol_droba]:
 > Looking at the problem again, I think that the problem actually lies in
 Solaris's C++ locales. There is nothing wrong with chars being signed.
 >
 > Anyway, I'll try to check it out and come up with a solution.

 I'm coming to that conclusion, too.

 The C versions of `tolower`, et. al. take an `int` as a parameter. The C99
 standard (section 7.4.1) says that the input to tolower needs to be
 representable as unsigned char, or EOF. To me that means "no negative
 numbers". Microsoft has a page that talks about this issue, too:
 http://msdn.microsoft.com/en-us/library/ms245348.aspx


 However, the C++ version `std::tolower`, takes a `char` (templated) as a
 parameter, and I can't find any similar restriction in either the C++03
 standard or the (draft) C++11 standard. To me, that means that all
 possible values of `char` are allowable (or whatever type the function is
 templated upon)

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3634#comment:6>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.