Wrong encoding when getting a string from MySQL database with C++

Question

I'm writing an MFC app with C++ in Visual Studio 2012. App connects to a MySQL database and shows every row to a List Box. Words are in Russian, database encoding is cp1251. I've set the same character set using this code:

if (!mysql_set_character_set(mysql, "cp1251")) {
    statusBox.SetWindowText((CString)"CP1251 is set for MYSQL.");
}

But it doesn't help at all. I display data using this code:

while ((row = mysql_fetch_row(result)) != NULL) {
    CString string = (CString)row[1];
    listBox.AddString(string);
}

This code also doesn't help:

mysql_query(mysql, "set names cp1251");

Please help. What should I do to display cyrillic correctly?

Answer 1

When crossing system boundaries that use different character encodings you have to convert between them. In this case, the MySQL database uses CP 1251 while Windows (and CString ) use UTF-16. The conversion might look like this:

#if !defined(_UNICODE)
    #error Unicode configuration required
#endif

CString CPtoUnicode( const char* CPString, UINT CodePage ) {
    CString retValue;
    // Retrieve required string length
    int len = MultiByteToWideChar( CodePage, 0,
                                   CPString, -1,
                                   NULL, 0 );
    if ( len == 0 ) {
        // Error -> return empty string
        return retValue;
    }

    // Allocate CString's internal buffer
    LPWSTR buffer = retValue.GetBuffer( len );
    // Do the conversion
    MultiByteToWideChar( CodePage, 0,
                         CPString, -1,
                         buffer, len );
    // Return control of the buffer back to the CString object
    retValue.ReleaseBuffer();
    return retValue;
}

This should be used as follows:

while ( ( row = mysql_fetch_row( result ) ) != NULL ) {
    CString string = CPtoUnicode( row[1], 1251 );
    listBox.AddString( string );
}

Alternatively, you could use CString s built-in conversion support, which requires to set the thread's locale to the source encoding (CP 1251) and use the conversion constructor.