Open utf8 encoded filename in c++ Windows -


consider following code:

#include <iostream> #include <boost\locale.hpp> #include <windows.h> #include <fstream>  std::string toutf8(std::wstring str) {     std::string ret;     int len = widechartomultibyte(cp_utf8, 0, str.c_str(), str.length(), null, 0, null, null);     if (len > 0)     {         ret.resize(len);         widechartomultibyte(cp_utf8, 0, str.c_str(), str.length(), &ret[0], len, null, null);     }     return ret; }  int main() {     std::wstring wfilename = l"d://private//test//एउटा फोल्दर//भित्रको फाईल.txt";     std::string utf8path = toutf8(wfilename );     std::ifstream ifilestream(utf8path , std::ifstream::in | std::ifstream::binary);     if(ifilestream.is_open())     {         std::cout << "opened file\n";         //do work here.     }     else     {         std::cout << "cannot opened file\n";      }     return 0;  }

if running file, cannot open file entering else block. using boost::locale::conv::from_utf(utf8path ,"utf_8") instead of utf8path doesn't work. code works if consider using wifstream , using wfilename parameter, don' want use wifstream. there way open file name utf8 encoded? using visual studio 2010.

on windows, must use 8bit ansi (and must match user's locale) or utf16 filenames, there no other option available. can keep using string , utf8 in main code, have convert utf8 filenames utf16 when opening files. less efficient, need do.

fortunately, vc++'s implementation of std::ifstream , std::ofstream have non-standard overloads of constructors , open() methods accept wchar_t* strings utf16 filenames. 

explicit basic_ifstream(     const wchar_t *_filename,     ios_base::openmode _mode = ios_base::in,     int _prot = (int)ios_base::_openprot );  void open(     const wchar_t *_filename,     ios_base::openmode _mode = ios_base::in,     int _prot = (int)ios_base::_openprot ); void open(     const wchar_t *_filename,     ios_base::openmode _mode ); 

explicit basic_ofstream(     const wchar_t *_filename,     ios_base::openmode _mode = ios_base::out,     int _prot = (int)ios_base::_openprot );  void open(     const wchar_t *_filename,     ios_base::openmode _mode = ios_base::out,     int _prot = (int)ios_base::_openprot ); void open(     const wchar_t *_filename,     ios_base::openmode _mode );

you have use #ifdef detect windows compilation (unfortunately, different c++ compilers identify differently) , temporarily convert utf8 string utf16 when opening file.

#ifdef _msc_ver std::wstring toutf16(std::string str) {     std::wstring ret;     int len = multibytetowidechar(cp_utf8, 0, str.c_str(), str.length(), null, 0);     if (len > 0)     {         ret.resize(len);         multibytetowidechar(cp_utf8, 0, str.c_str(), str.length(), &ret[0], len);     }     return ret; } #endif  int main() {     std::string uft8path = ...;     std::ifstream ifilestream(         #ifdef _msc_ver         toutf16(uft8path).c_str()         #else         uft8path.c_str()         #endif         , std::ifstream::in | std::ifstream::binary);     ...     return 0; }

note guaranteed work in vc++. other c++ compilers windows not guaranteed provide similar extensions.


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