Re: [Boost-Users] Re: Regex and Unicode

From: John Maddock (john_maddock_at_[hidden])
Date: 2002-09-20 05:39:09

> >> I'm trying to use Unicode with Regex in an MFC app. The preprocessor
> >> variable UNICODE is defined. But I obtain an error on the line :
> >>
> >> regex_search(sText, oResults, pRegExp);
> >> error C2665: none of the 4 overloads can convert parameter 1 from
> >> type 'class CString'
> >>
> >> sText is a CString which has a "const wchar_t*" operator. The
> >> problem is why doesn't the regex_search prototype require a "const
> >> wchar_t*" when UNICODE is defined ?
> >
> > You did, use sText.c_str() to get a const wchat_t*, otherwise there
> > are too many overloaded forms of the function for the conversion to
> > be found automatically.
>
> I tried the "const wchar_t*" operator :
> regex_search((const wchar_t*) sText, oResults, pRegExp);
> but the problem is not here.
> VC++6 wrote :
> error C2664: '__thiscall boost::reg_expression<char,class
> boost::regex_traits<char>,class
boost::detail::allocator_adapter<char,class
> boost::detail::simple_alloc> >::boost::reg_expression<char,class
> boost::regex_traits<char>,class
boost::detail::allocator_adapter<char,class
> boost::detail::simple_alloc> >(const class
> boost::detail::allocator_adapter<char,class boost::detail::simple_alloc>
&)'
> : cannot convert parameter 1 from 'const unsigned short *' to 'const class
> boost::detail::allocator_adapter<char,class boost::detail::simple_alloc>
&'
>         Reason: cannot convert from 'const unsigned short *' to 'const
class
> boost::detail::allocator_adapter<char,class boost::detail::simple_alloc>'
>         No constructor could take the source type, or constructor overload
> resolution was ambiguous
>
> You see that the reg_expression prototype contains "char"s and not
> "wchar_t"s.
> Are you sure that the only thing to do to use UNICODE is to put a #define
> UNICODE (I put it in my stdafx.h and in my project settings)?

Sorry, let me try again: the only effect that defining UNICODE has on the
regex lib is on the definition of the POSIX C API functions.  All the
template classes and functions remain unchanged.  So you need to be using
boost::wregex not boost::regex for your regular expressions.

John Maddock
http://ourworld.compuserve.com/homepages/john_maddock/index.htm