QByteArray::fromBase64() and QTextCodec::toUnicode problem

[Mahoney]

Hi. I'm parsing an email message headers. The strings are encoded with Base64 algoritm and are in KOI8-R codepage.
I do the following:

QByteArray a = QByteArray::fromBase64(src);
// here in 'a' I have decoded text in KOI8-R encoding
QTextCodec *pCodec = QTextCodec::codecForName("koi8-r");
QByteArray b = pCodec->toUnicode(a).toUtf8();
// in 'b' I have garbage instead of desired text

QByteArray a = QByteArray::fromBase64(src);
// here in 'a' I have decoded text in KOI8-R encoding
QTextCodec *pCodec = QTextCodec::codecForName("koi8-r");
QByteArray b = pCodec->toUnicode(a).toUtf8();
// in 'b' I have garbage instead of desired text

To copy to clipboard, switch view to plain text mode 

What's wrong with the code?

[bibhukalyana]

try this.

QTextCodec *codec = QTextCodec::codecForName("KOI8-R");
 QTextDecoder *decoder = codec->makeDecoder();
 
 QString string;
 while (new_data_available()) {
     QByteArray chunk = get_new_data();
     string += decoder->toUnicode(chunk);
 }
 delete decoder;

QTextCodec *codec = QTextCodec::codecForName("KOI8-R");
 QTextDecoder *decoder = codec->makeDecoder();

 QString string;
 while (new_data_available()) {
     QByteArray chunk = get_new_data();
     string += decoder->toUnicode(chunk);
 }
 delete decoder;

To copy to clipboard, switch view to plain text mode 

[ChrisW67]

How are you determining that there is garbage in b and that the garbage is not in a or src?
Short example inputs and expected/actual outputs?