conversion from 'QTableWidgetItem* const' to 'QChar' ..or QString...is ambiguous - c++

Question

I am studying qt - and in the book C++ GUI Programming With Qt 4 I am trying to get all code to work. I am having problems with converting a selection of the contents from a custom table widget into plain text.
existing code in the book:
void MyTableWidget::mouseMoveEvent(QMouseEvent *event)
{
if (event->buttons() & Qt::LeftButton) {
int distance = (event->pos() - startPos).manhattanLength();
if (distance >= QApplication::startDragDistance())
performDrag();
}
QTableWidget::mouseMoveEvent(event);
}
void MyTableWidget::performDrag()
{
QString plainText = selectionAsPlainText();
if (plainText.isEmpty())
return;
QMimeData *mimeData = new QMimeData;
mimeData->setText(plainText);
mimeData->setHtml(toHtml(plainText));
mimeData->setData("text/csv", toCsv(plainText).toUtf8());
QDrag *drag = new QDrag(this);
drag->setMimeData(mimeData);
if (drag->exec(Qt::CopyAction | Qt::MoveAction) == Qt::MoveAction)
deleteSelection();
}
I am trying to write selectionAsPlainText() and deleteSelection().
QTableWidgetSelectionRange MyTableWidget::selectedRange() const
{
QList<QTableWidgetSelectionRange> ranges = selectedRanges();
if (ranges.isEmpty())
return QTableWidgetSelectionRange();
return ranges.first();
}
QString MyTableWidget::selectionAsPlainText()
{
QTableWidgetSelectionRange range = selectedRange();
QList<QTableWidgetItem *> items = selectedItems();
QString str;
for (int i=0;i<range.rowCount();i++){
for (int j=0;j<range.columnCount();j++){
// error on this line
str+=QString(items.at(i*(range.columnCount()-1)+j)->data(Qt::DisplayRole)));
if (j!= range.columnCount()-1)
str += "\t";
}
str += "\n";
}
return str;
}
In this try, out of many, I am attempting to place the items from the QTableWidgetItem in a QString, separated either by "\t" or "\n".
I am unable to try any type of such action because I am getting errors in trying to place any content into the QString.
Everything I have tried so far gives me an error like
conversion from 'QTableWidgetItem* const' to 'QChar' is ambiguous
or
error: no matching function for call to 'QString::QString(QVariant)'
I don't know how to make this type conversion, I have not seen examples on how to specify type casting... Though as I understand it, selecting the Qt::DisplayRole of the data, I should implicitly have a QString...
How can I make this type conversion work ?
I included more code to suggest that the TableWidget is likely of an unknown type.

Answer 1

To begin with, heavily nested parentheses are difficult to read. I would recommend splitting the offending line into several lines. Secondly, the type returned from QTableWidgetItem::data is a QVariant, which can be converted to a QString using the QVariant::toString() member function. Also, I don't think i*(range.columnCount()-1) is quite what you want.
Given this, your code should look something like the following:
int index = i*range.columnCount()+j;
QTableWidgetItem* item = items.at(index);
str += item->data(Qt::DisplayRole).toString();