New subject: lexical_cast and string to wstring!

21 Mar 2006

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-----Original Message-----
From: Thomas Gulbrandsen [mailto:thomas@tansa.no]
Sent: Tuesday, March 21, 2006 11:30 AM
To: boost-users@lists.boost.org
Subject: [Boost-users] lexical_cast and string to wstring!
Hello!
I have to convert a std::wstring to a std::string and tried the
following
small test program.
...
But this will not compile on MSVC8.0 or MSVC7.1.
Is the boost::lexical_cast suppost to handle this conversion?
As far I know, it's not (corrections, anybody?).  My usual method to
perform this conversion on Windows is to use WideCharToMultiByte, found
in the Windows Platform SDK.  Note, however, this function is designed
to work with C-style strings and/or fixed-width.  You might consider a
function similar to the following (warning: untested code):

#include <string>
#include 

std::string NarrowString (const std::wstring &src)
{
	//A temporary buffer to store the converted string.
	//It must be large enough to store the string.
	char buffer[100];

	//Convert the string to UTF-8 and store it in the local buffer.
	//If you're looking for your native encoding, replace
	//CP_UTF8 with CP_ACP and look into the dwFlags, lpDefaultChar,
and
	//lpUsedDefaultChar parameters to WideCharToMultiByte.
	int narrowWidth = WideCharToMultiByte (CP_UTF8, 0,
		src.data(), src.length(), buffer, sizeof buffer,
		NULL, NULL);

	//Convert the buffer to a string and return it
	return std::string (buffer, narrowWidth);
}

Other platforms have a similar facility.  If you're looking for a
cross-platform solution, I would recommend the ICU library.  Also, as I
understand it, ICU is the "similar facility" for several variants of
Unix.

Re: [Boost-users] lexical_cast and string to wstring!

Andrew Holden

Thomas Gulbrandsen

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