Hi, Scott,
On Fri, Nov 27, 2015 at 1:01 AM, Scott Robison <scott at casaderobison.com>
wrote:
> On Thu, Nov 26, 2015 at 10:13 PM, Igor Korot <ikorot01 at gmail.com> wrote:
>>
>> Hi,
>> Is there any way to have "sqlite3_errmsg" function return a wide char
> string?
>> Or do a conversion in a portable way?
>>
>> Thank you.
>
> The portable way would be to use the mbstowcs function from stdlib.h,
> though it depends on what locales are supported by the system, so maybe not
> as portable as you would like.
I should've been more explicit here, sorry.
I'm developing in C++ and need to convert to std::wstring.
Or maybe I can just generate my own error message based on the sqlite
return code?
Thank you.
>
> There isn't really a truly portable way of converting from char to wchar_t
> based strings, given that there is no real guarantee about what exactly
> wchar_t *is*. The ISO C90 standard merely defined it as "an integral type
> whose range of values can represent distinct codes for all members of the
> largest extended character set specified among the supported locales". In
> theory, wchar_t could be a typedef of char if a platform only supported an
> 8 bit character set. Unicode was being designed at the time of C
> standardization, but the first version of Unicode wasn't published for a
> year or more after the C90 standard. Thus the wchar_t type doesn't have to
> be Unicode,
>
> In practical terms, I generally consider wchar_t to be a pre-2011 method of
> storing Unicode. Even here there are no portability guarantees. Microsoft
> went all in on Unicode in the early 1990s, back when it was only a two byte
> encoding (UCS-2), so Microsoft compilers treat wchar_t as a two byte type.
> Unicode 2.0 extended the Unicode character set in 1996 (I think) and
> introduced UTF-16 as a compromise way of allowing systems that embraced
> Unicode 1.0 (when it "guaranteed" a 16 bit character space) to support the
> full space of Unicode code points from U+0000 to U+10FFFF via surrogate
> pairs. Modern posix systems (as far as I know) define wchar_t to be a 32
> bit type, so you can't really convert to wchar_t in a portable way, because
> you have to handle surrogate pairs on Windows vs simple code points in
> posix (though this should be handled by mbstowcs if the platform supports
> wchar_t as unicode).
>
> If you only use ASCII or Latin-1 8 bit characters in your code, or are
> willing to treat all char objects as ASCII or Latin-1, then you can convert
> char strings to wchar_t strings by simply zero extending each character
> while copying it. Something like this (without any error checking):
>
> void copy_narrow_to_wide(wchar_t* dst, const char* src)
> {
> while (*src) *(dst++) = (unsigned char)(*(src++));
> *dst = 0;
> }
>
> --
> Scott Robison
> _______________________________________________
> sqlite-users mailing list
> sqlite-users at mailinglists.sqlite.org
> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
