Windows Unicode C++ Stream Output Failure

To write into a file, you have to set the locale correctly, for example if you want to write them as UTF-8 characters, you have to add

const std::locale utf8_locale
            = std::locale(std::locale(), new std::codecvt_utf8<wchar_t>());
test_file.imbue(utf8_locale);

You have to add these 2 include files

#include <codecvt>
#include <locale>

To write to the console you have to set the console in the correct mode (this is windows specific) by adding

_setmode(_fileno(stdout), _O_U8TEXT);

(in case you want to use UTF-8).

For this you have to add these 2 include files:

#include <fcntl.h>
#include <io.h>

Furthermore you have to make sure that your are using a font that supports Unicode (such as for example Lucida Console). You can change the font in the properties of your console window.

The complete program now looks like this:

#include <fstream>
#include <iostream>
#include <codecvt>
#include <locale>
#include <fcntl.h>
#include <io.h>

int main()
{

  const std::locale utf8_locale = std::locale(std::locale(),
                                    new std::codecvt_utf8<wchar_t>());
  {
    std::wofstream test_file("c:\\temp\\test.txt");
    test_file.imbue(utf8_locale);
    test_file << L"\u2122";
  }

  _setmode(_fileno(stdout), _O_U8TEXT);
  std::wcout << L"\u2122";
}