Take the 2-minute tour ×
Code Review Stack Exchange is a question and answer site for peer programmer code reviews. It's 100% free, no registration required.

I've recently had to print some national symbols in windows console using Mingw and found, that I got nothing in the output, if I use wide strings.

So, I studied the problem and found out that it is locale problem. I was unable to find somewhere complete solution, so I had to write something, that seems to work.

So, I decided to publish it here for review, or may be I should publish it somewhere it it worth.

  • I've tested in Mingw 4.7.0 using Russian locale.
  • It should probably correctly convert wide strings to national OEM encoded strings.

Code:

#ifndef CUSTOM_LOCALE_H
#define CUSTOM_LOCALE_H

#if (__cplusplus >= 201103L)
#define CUSTOM_LOCALE_OVERRIDE override
#else 
#define CUSTOM_LOCALE_OVERRIDE
#endif

#include <locale>
#include <iostream>
#include <windows.h>

namespace custom_locale
{

class CustomLocale : public std::codecvt <wchar_t, char, std::mbstate_t> {
  public:
    explicit CustomLocale ( size_t r = 0 ) : std::codecvt <wchar_t, char, std::mbstate_t> (r) {}

  protected:
    result do_in (state_type&, const char* from, const char* from_end, 
                  const char*& from_next, wchar_t* to, wchar_t* to_end, wchar_t*& to_next ) const CUSTOM_LOCALE_OVERRIDE
    {
        std::size_t size = from_end - from;
        std::size_t buffer_size = to_end - to;
        std::size_t written = MultiByteToWideChar(CP_OEMCP, 0, from, size, to, buffer_size);
        to_next = to + written;
        if (written == 0) {
            return error;
        }
        else if (written != buffer_size) {
            return partial;
        }
        else {
            return  ok;
        }
    }

    result do_out (state_type&, const wchar_t* from, const wchar_t* from_end, 
                   const wchar_t*& from_next, char* to, char* to_end, char*& to_next ) const CUSTOM_LOCALE_OVERRIDE
    {
        std::size_t size = from_end - from;
        std::size_t buffer_size = to_end - to;
        std::size_t written = WideCharToMultiByte(CP_OEMCP, 0, from, size, to, buffer_size, 0, 0);
        to_next = to + written;
        if (written == 0) {
            return error;
        }
        else if (written != buffer_size) {
            return partial;
        }
        else {
            return  ok;
        }
    }

    result do_unshift ( state_type&, char*, char*, char*& ) const CUSTOM_LOCALE_OVERRIDE { return ok; }
    int do_encoding () const throw () CUSTOM_LOCALE_OVERRIDE { return 1; }
    bool do_always_noconv () const throw () CUSTOM_LOCALE_OVERRIDE { return false; }

    int do_length ( state_type& state, const char* from, const char* from_end, size_t max ) const CUSTOM_LOCALE_OVERRIDE 
    {
      return std::codecvt <wchar_t, char, std::mbstate_t>::do_length ( state, from, from_end, max );
    }

    int do_max_length () const throw () CUSTOM_LOCALE_OVERRIDE
    {
      return std::codecvt <wchar_t, char, std::mbstate_t>::do_max_length ();
    }
};

inline void init()
{
    std::locale loc ( std::locale(), new CustomLocale() );
    std::ios_base::sync_with_stdio (false);
    std::wcout.imbue(loc);
    std::wcin.imbue(loc);
} 

}

#endif

Example:

#include "custom_locale.h"

int main ()
{
    custom_locale::init();    
    std::wstring s(L"привет");
    std::wcout << s << '\n';
    std::wstring u; 
    std::wcin >> u;
    s += L' ' + u;
    std::wcout << s << '\n';
    return 0;
}
share|improve this question
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.