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I need to open a file as std::fstream (or actually any other std::ostream) when file name is "Unicode" file name.

Under MSVC I have non-standard extension std::fstream::open(wchar_t const *,...) ? What can I do with other compilers like GCC (most important) and probably Borland compiler.

I know that CRTL provides _wfopen but it gives C FILE * interface instead of io-streams, maybe there is a non-standard way to create io-stream from FILE * ? Is there any boost::ifstream with MSVC like extension for Windows?

You can't. On Mac OS X it was decided that the POSIX file api's - and hence std::fstream - would all take utf-8. In environments where there are not platform specific extentions (such as gcc and bc on windows (actually, they might have their own extensions, but that would be outside of the POSIX standard)) the c & c++ runtime functions cannot be expected to reliably access the filesystem given files with non ascii characters in their name. – Chris Becke Feb 23, 2010 at 9:48 @Chris I have no problems with library that supports UTF-8 - it is perfect for me. The issue that Windows does not support UTF-8 – Artyom Feb 23, 2010 at 10:42 a hackish workaround for MinGW is in stackoverflow.com/questions/6524821/opening-stream-via-function – marcin Mar 2, 2015 at 19:03

Unfortunately, there's no standard way to do that, although C++0x (1x?) promises to do that. Until then, you properly assumed that a solution can be found in Boost, however, the library you're searching for is Boost.Filesystem .

Boost.Filesystem internally uses wide strings by default for its universal path system, so there are no unicode problems in this regard.

Do you have a reference for C++0X? I remember discussions but no conclusion and I found nothing in the latest draft. – AProgrammer Feb 23, 2010 at 9:30 The problem is the boost::filesystem does not supports wpath under MinGW/GCC because boost configuration defines BOOST_NO_STD_WSTRING for some reason (even wide strings work quite well under mingw) – Artyom Feb 23, 2010 at 11:04 I've searched a little more and found this: open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#454 , apparently no solution before library TR2. – AProgrammer Feb 23, 2010 at 19:53 I think it is not good solution to add wchar_t . I think that MS CRTL just should support UTF-8 strings instead. Windows is only operating system that uses wide API for core parts. – Artyom Feb 24, 2010 at 6:19 @art the issue is that windows supported unicode before utf8 was invented and wide was the best choice at that time. The die is now cast. – David Heffernan Jun 19, 2011 at 7:16 _wfopen is windows specific, guess boost resolves according to platform?! stackoverflow.com/a/35065142/9437799 – Sam Ginrich Apr 20, 2022 at 8:15

Convert the Unicode filename to a char* string using something like wcstombs() or WideCharToMultiByte() (which gives you far more control over the codepages involved).

Then use the converted filename to open the file.

File name includes unicode characters that may not be represented in current locale codepage (i.e. Hebrew characters can't be represented in Latin1 8-bit locale), also Windows does not support UTF-8 code pages. So no, this does not work. – Artyom Feb 23, 2010 at 9:23 covers most of the practical use cases with special characters, where that MS- MultiByte actually has been ANSI – Sam Ginrich Jul 9, 2022 at 9:48

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