You wouldn't imagine something as basic as opening a file using the C++ standard library for a Windows application was tricky … but it appears to be. By Unicode here I mean UTF-8, but I can convert to UTF-16 or whatever, the point is getting an ofstream instance from a Unicode filename. Before I hack up my own solution, is there a preferred route here ? Especially a cross-platform one ?
C++ – How to open an std::fstream (ofstream or ifstream) with a unicode filename
cunicodewindows
Best Answer
The C++ standard library is not Unicode-aware.
char
andwchar_t
are not required to be Unicode encodings.On Windows,
wchar_t
is UTF-16, but there's no direct support for UTF-8 filenames in the standard library (thechar
datatype is not Unicode on Windows)With MSVC (and thus the Microsoft STL), a constructor for filestreams is provided which takes a
const wchar_t*
filename, allowing you to create the stream as:However, this overload is not specified by the C++11 standard (it only guarantees the presence of the
char
based version). It is also not present on alternative STL implementations like GCC's libstdc++ for MinGW(-w64), as of version g++ 4.8.x.Note that just like
char
on Windows is not UTF8, on other OS'eswchar_t
may not be UTF16. So overall, this isn't likely to be portable. Opening a stream given awchar_t
filename isn't defined according to the standard, and specifying the filename inchar
s may be difficult because the encoding used by char varies between OS'es.