Re: Conversion of byte array to cstring

From:

"Giovanni Dicanio" <giovanni.dicanio@invalid.it>

Newsgroups:

microsoft.public.vc.mfc

Date:

Fri, 24 Aug 2007 01:06:33 +0200

Message-ID:

<eHJntpd5HHA.4584@TK2MSFTNGP03.phx.gbl>

"AliR (VC++ MVP)" <AliR@online.nospam> ha scritto nel messaggio
news:SFhzi.4581$LL7.4217@nlpi069.nbdc.sbc.com...

What kind of conversion are we talking about, what is the byte array
representing? Does the byte array have 0 anywhere in it?

Here is one way

CString Buffer;
for (int i = 0; i < Array.Length();i++)
{
Buffer += (TCHAR)Array.GetAt(i);
}

Hello Alir,

I don't want to be picky, but I don't like very much the above TCHAR cast...

I think that the above code could be OK *without the TCHAR cast*, if Array
stores BYTEs, which are the ANSI characters to be put in the CString.
But if the input array stores bytes for Unicode UTF-16 strings, I think that
it would not be correct.

I think that a code like the following could be OK, with two separate
branches for ANSI and Unicode (UTF-16):

<code>
///////////////////////////////////////////////////////////
// An array storing BYTEs
///////////////////////////////////////////////////////////
typedef std::vector< BYTE > ByteArray;

///////////////////////////////////////////////////////////
// Build a ANSI string from characters stored into a
// byte array
///////////////////////////////////////////////////////////
CStringA BuildAnsiString( const ByteArray & chars )
{
    if ( chars.empty() )
        return "";

    const int charsCount = static_cast<int>( chars.size() );
    CStringA str( ' ', charsCount );
    for ( int i = 0; i < charsCount; i++ )
    {
        str.SetAt( i, chars[ i ] );
    }

    return str;
}

///////////////////////////////////////////////////////////
// Build a Unicode UTF-16 string from characters stored
// into a byte array
///////////////////////////////////////////////////////////
CStringW BuildUnicodeString( const ByteArray & chars )
{
    if ( chars.empty() )
        return L"";

    // Unicode chars count
    const int charsCount = static_cast<int>( chars.size() ) / 2;

    CStringW str( ' ', charsCount );
    const BYTE * pBytes = &chars[0];
    for ( int i = 0; i < charsCount; i++ )
    {
        // Build the Unicode UTF-16 code-point
        WCHAR wch = MAKEWORD( *pBytes, *(pBytes+1) );

        // Point to next WCHAR in source array
        pBytes += 2;

        // Update string character
        str.SetAt( i, wch );
    }

    return str;
}

//
// TEST
//
void Test()
{

    //
    // ANSI Test
    //
    ByteArray ansiChars;
    ansiChars.push_back( 0x48 ); // H
    ansiChars.push_back( 0x49 ); // I

    CStringA strAnsi = BuildAnsiString( ansiChars );
    CA2W s( strAnsi );
    AfxMessageBox( s );

    //
    // Unicode Test
    //
    ByteArray charsUnicode;
    charsUnicode.push_back( 0xB1 ); // alpha
    charsUnicode.push_back( 0x03 );

    charsUnicode.push_back( 0xB4 ); // delta
    charsUnicode.push_back( 0x03 );

    CStringW strUnicode = BuildUnicodeString( charsUnicode );
    AfxMessageBox( strUnicode );
}

</code>

Maybe the OP was not very clear about the content of his byte-array...

Giovanni