Re: Multi language application

Hi,

I think that if you want to correctly display Unicode characters in Windows,
you must use UTF-16 (which is the Unicode encoding used internally by
Windows).

However, if for some reasons you do want to use UTF-8 inside your
application, I think that you can do that (e.g. storing your strings in
CStringA or std::string), and then you can just convert your UTF-8 strings
to UTF-16 just before passing them to Windows controls (like edit control)
for display.

You can use ::MultiByteToWideChar Win32 API to convert from UTF-8 to UTF-16,
and pass the UTF-16 string to Windows controls.

e.g.

<code>

  // Your UTF-8 string
  CStringA utf8;
  ... process your utf8 string ...
  ...

  // Convert UTF-8 string to Unicode UTF-16
  // to be used by Windows
  CStringW utf16 = ConvertUtf8ToUtf16( utf8 );

  // Pass the UTF-16 string to Windows
  ... e.g.
  pSomeEditCtrl->SetWindowText( utf16 );

</code>

I can share a function I developed to convert strings from UTF-8 to UTF-16,
feel free to use that in your code, if you need:

<code>

// ======================================================================
//
// FUNCTION: ConvertUtf8ToUtf16
// AUTHOR: Giovanni Dicanio
//
// Converts from Unicode UTF-8 string to UTF-16.
//
// On error: ASSERTs in debug builds; in release builds throws using
// AtlThrow or AtlThrowLastWin32 (see documentations of these functions
// for more details).
//
// This function should work since VS2003 (VC++7.1), but not on VC6,
// because of lack of newer ATL-MFC shared classes and functions like
// CStringA/W in VC6.
//
// ======================================================================
CStringW ConvertUtf8ToUtf16( const CStringA & utf8 )
{
    //
    // Special case of empty string
    //
    if ( utf8.IsEmpty() )
    {
        return L"";
    }

    //
    // Consider byte count corresponding to total string length,
    // including end-of-string (\0) character
    //
    const int utf8ByteCount = utf8.GetLength() + 1;

    //
    // Get size of destination UTF-16 buffer, in wchar_t's
    //
    int utf16Size = ::MultiByteToWideChar(
        CP_UTF8, // convert from UTF-8
        MB_ERR_INVALID_CHARS, // error on invalid chars
        static_cast<const char *>(utf8), // source UTF-8 string
        utf8ByteCount, // total length of source UTF-8 string,
                                // in bytes, including end-of-string \0
        NULL, // unused - no conversion done in this step
        0 // request size of destination buffer, in wchar_t's
    );
    ATLASSERT( utf16Size != 0 );
    if ( utf16Size == 0 )
    {
        AtlThrowLastWin32();
    }

    //
    // Allocate destination buffer to store UTF-16 string
    //
    std::vector< wchar_t > utf16Buffer( utf16Size );

    //
    // Do the conversion from UTF-8 to UTF-16
    //
    int result = ::MultiByteToWideChar(
        CP_UTF8, // convert from UTF-8
        MB_ERR_INVALID_CHARS, // error on invalid chars
        static_cast< const char *>(utf8), // source UTF-8 string
        utf8ByteCount, // total length of source UTF-8 string,
                                // in bytes, including end-of-string \0
        &utf16Buffer[0], // destination buffer
        utf16Size // size of destination buffer, in wchar_t's
    );
    ATLASSERT( result != 0 );
    if ( result == 0 )
    {
        AtlThrowLastWin32();
    }

    //
    // Build UTF-16 string from conversion buffer
    //
    return CStringW( &utf16Buffer[0] );
}

</code>

HTH,
Giovanni

"Nord Pierre" <non> ha scritto nel messaggio
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