I need a code in C++ to convert a string given in wchar_t* to a UTF-16 string. It must work both on Windows and Linux. I've looked through a lot of web-pages during the search, but the subject still is not clear to me.
As I understand I need to:
setlocale with LC_TYPE and UTF-16 encoding.wcstombs to convert wchar_t to UTF-16 string.setlocale to restore previous locale.Do you know the way I can convert wchar_t* to UTF-16 in a portable way (Windows and Linux)?
There is no single cross-platform method for doing this in C++03 (not without a library). This is in part because wchar_t is itself not the same thing across platforms. Under Windows, wchar_t is a 16-bit value, while on other platforms it is often a 32-bit value. So you would need two different codepaths to do it.
C++11's std::codecvt_utf16 should work, I think.
std::codecvt_utf16 is a std::codecvt facet which encapsulates conversion between a UTF-16 encoded byte string and UCS2 or UCS4 character string (depending on the type of Elem).
See this: http://en.cppreference.com/w/cpp/locale/codecvt_utf16
<codecvt> header yet, so std::codecvt_utf16 is not available.
char16_t and char32_t types (and associated std::basic_string typedefs) to get away from wchar_t platform issues. For instance, use std::u16string wherever you need a UTF-16 encoded string.You can assume that wchar_t is utf-32 in the non-Windows world. It is true on Linux and Mac OS X and most *nix systems (there are very few exceptions to that, and on systems you will probably never touch :-)
And wchar_t is utf-16 on Windows. So on Windows the conversion function can just do a memcpy :-)
On everything else, the conversion is algorithmic, and pretty simple. So there is no need of fancy support from 3rd party libraries.
Here is the basic algorithm: http://unicode.org/faq/utf_bom.html#utf16-3
And you can probably find find a dozen different implementations if you don't want to write your own :-)
The problem is with wchar_t being rather underspecified. You could use GNU libiconv to do what you want. It accepts special encoding name "wchar_t" as both source and target encoding. That way it will be portable to both Windows and Linux and elsewhere where you can provide libiconv.
The g++ compiler appears to support wcstombs?
wchar_tstring in? What type do you expect to use to represent the character type in the UTF-16 string? Is this simply a transform between UTF-32 (in thewchar_t) and UTF-16 inuint16_t? Or are you dealing with codeset conversion too? Portability is a noble goal; it is not always achievable, sadly. Do investigate ICU.