QPieSeries::slices() strange behavior

cpper


    QPieSeries* series= new QPieSeries;
    QList<QPieSlice* > sliceList;

    sliceList.append(new QPieSlice("una",5));
    sliceList.append(new QPieSlice("doua",20));

    series->append(sliceList);

    QList<QPieSlice*>::iterator it1 = series->slices().end() -1;
    QList<QPieSlice*>::iterator it2 =        sliceList.end() -1;

    qDebug()<<*it1;
    qDebug()<<*it2;

qDebug()<<*it1; line crashes the program. Shouldn't series->slices() contain the same pointers to QPieSlice as sliceList does? I can't understand what is wrong in the code. Any ideas ?

kshegunov

@cpper said in QPieSeries::slices() strange behavior:

Shouldn't series->slices() contain the same pointers to QPieSlice as sliceList does? I can't understand what is wrong in the code. Any ideas ?

You're taking an iterator (a pointer) to a temporary. When the temporary is destroyed the iterator becomes invalid and when you call the dereference operator on it, you get a crash.

cpper

Oops...I understand what you mean. If slices() had returned a reference to the list of the slices my code made sense. I think.
Thanks :)

kshegunov

@cpper said in QPieSeries::slices() strange behavior:

If slices() had returned a reference to the list of the slices my code made sense.

If it did it would, yes. Now your iterator is pointing to a piece of memory that's been freed.