Qt C++ - QDataStream not reading boolean values

Question

Hello world, I am working on a project where i can serialize a n object in a file and read it later but when i write the values(boolean value), it works but when i try to read them, this is what i get:

binary '>>' : no operator found which takes a right-hand operand of type bool(or there is no acceptable conversion)

This is my code

      void MainWindow::writeSettings()
      {
         QFile *settingsFile = new QFile(":/images/settings_file.txt");

         if(!settingsFile->open(QIODevice::WriteOnly))
         {
          qDebug() << "File not responsing";

         } else
         {
           QDataStream out(settingsFile);
          out.setVersion(QDataStream::Qt_5_3);
          out << settings->getEnableWordWrap();
          out << settings->getShowStatusbar();
          out << settings->getShowToolbar();
}

settingsFile->flush();
settingsFile->close();

}

Now if i try to read, get the error

         QFile selc(":/images/settings_file.txt");

if(!selc.open(QIODevice::ReadOnly))
{
    qDebug() << "File not responding";
} else
{
    QDataStream in(&selc);
    in >> settings->getEnableWordWrap() >> settings->getShowStatusbar() >> settings->getShowToolbar();
}

selc.close();

getEnableWordWrap(), getShowStatusbar() and getShowToolbar() are all boolean return types.

epsilon epsilon · Accepted Answer · 2014-08-26T12:59:58

You are trying to change a value, the one provide by your getter.

You should prefer extracting your bool values from your stream, before passing them to the right setter:

QDataStream in(&selc);
bool tmp;
in >> tmp;
settings->setEnableWordWrap(tmp);
in >> tmp;
settings->setShowStatusbar(tmp);
in >> tmp;
settings->setShowToolbar(tmp);

A more oriented object way to achieve that with Qt is to define these two methods to handle QDataStream serialization:

QDataStream &operator<<(QDataStream &, const MySettings &);
QDataStream &operator>>(QDataStream &, MySettings &);

Hence, you can deserialize your settings like this:

QDataStream in(&selc);
in >> settings;

Qt C++ - QDataStream not reading boolean values

1 Answers