Re: help - writing text to a file

From:
MrAsm <mrasm@usa.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Thu, 12 Apr 2007 15:27:40 GMT
Message-ID:
<ngjs13d3itofk9h8qlp7tcsfjs4l1f1aij@4ax.com>
On Wed, 11 Apr 2007 20:13:36 -0700, "Tom Serface"
<tom.nospam@camaswood.com> wrote:

You could use a CStdioFile to do this easily, not sure about the odd
characters showing though, but CStdioFile works with Unicode so if you're
using that you'll be safe with just about anything.


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

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