Re: help - writing text to a file

On Wed, 11 Apr 2007 20:13:36 -0700, "Tom Serface"
<tom.nospam@camaswood.com> wrote:


To me, it seems that CStdioFile is *not* working with Unicode, but
maybe I'm missing something...

However:
I wrote a simple MFC dialog-based app with a list-box.
I put some Unicode strings into the list-box, and then I save them to
file.

Using both OP's method and CStdioFile fail (when you open the file,
the Chinese Unicode characters aren't there).

Instead, I converted the Unicode (Windows UTF-16) to Unicode UTF-8,
and then wrote the UTF-8 buffer to file.
In this way, I can reopen the file with a text editor, and I can see
the Chinese symbols, too.
(BTW: I wrote "Chinese symbols", but I don't know if they are Chinese
or Japanese or something else from Far East :)

Here's the code main code:

<CODE>
void CTestUnicodeTextDlg::OnBnClickedButton1()
{
    //
    // Put some Unicode strings in list
    //
    std::vector<CString> FileData;
    FileData.push_back(L"Ciao");
    FileData.push_back(L"C:\\Test");

    // UTF-16
    WORD chineseChars[] =
    {
        0x4E09,
        0x4E0B,
        0x4E11,
        0x0000,
    };
    FileData.push_back(CString((LPCWSTR) chineseChars));

    //
    // Show strings
    //
    m_List.ResetContent();
    for ( size_t i = 0; i < FileData.size(); i++ )
    {
        m_List.AddString( FileData.at(i) );
    }

    //
    // Write strings to file
    //

    // *** FAILS ***
    // ...Just writes ANSI...??
    //
    CStdioFile file(
        _T("test_cstdio.txt"),
        CFile::modeCreate | CFile::modeWrite | CFile::typeText
    );
    for( size_t i = 0; i < FileData.size(); i++)
    {
        CString line = FileData.at(i);
        line += L"\n";
        file.WriteString( line );
    }

    //
    // Save in UTF-8 format
    //
    FILE * fout = _wfopen( L"test_utf8.txt", L"wb" );
    for( size_t i = 0; i < FileData.size(); i++)
    {
        // Put the new line (\r\n)
        CString line(FileData.at(i));
        line += L"\r\n";

        // Convert from UTF-16 to UTF-8
        CW2U utf8String( line );

        // Send byte data to output file
        fwrite( (LPSTR) utf8String, 1, strlen(utf8String), fout );
    }
    fclose(fout);
    fout = NULL;
}

</CODE>

And here's the CW2U converter:

<CODE>
//----------------------------------------------------------------------------
// Class: CW2UEX
// Descr: Convert from Unicode UTF-16 (WideChars) to Unicode UTF-8
//----------------------------------------------------------------------------
template< int t_nBufferLength = 128 >
class CW2UEX
{
public:
    CW2UEX( LPCWSTR psz ) throw(...) :
        m_psz( m_szBuffer )
    {
        Init( psz );
    }

    ~CW2UEX() throw()
    {
        if( m_psz != m_szBuffer )
        {
            free( m_psz );
        }
    }

    operator LPSTR() const throw()
    {
        return( m_psz );
    }

private:
    void Init( LPCWSTR psz ) throw(...)
    {
        if (psz == NULL)
        {
            m_psz = NULL;
            return;
        }
        int nLengthW = lstrlenW( psz )+1;

        // One Unicode UTF-16 character could be converted
        // up to 4 UTF-8 characters
        int nLengthUtf8 = nLengthW * 4;

        if( nLengthUtf8 > t_nBufferLength )
        {
            m_psz = static_cast< LPSTR >( malloc(
                      nLengthUtf8*sizeof( char ) ) );
            if (m_psz == NULL)
            {
                AtlThrow( E_OUTOFMEMORY );
            }
        }

        if (::WideCharToMultiByte( CP_UTF8, 0, psz, nLengthW,
            m_psz, nLengthUtf8, NULL, NULL ) == 0)
        {
            AtlThrowLastWin32();
        }
    }

public:
    LPSTR m_psz;
    char m_szBuffer[t_nBufferLength];

private:
    CW2UEX( const CW2UEX& ) throw();
    CW2UEX& operator=( const CW2UEX& ) throw();
};

typedef CW2UEX<> CW2U;

</CODE>

MrAsm