QString copy-on-write example

QString str_a("Lorem ipsum dolor sit amet, consectetur adipiscing elit.");
qDebug() << str_a.constData(); // print out address of data buffer
// With copy-on-write strings, str_b does not yet allocate a new buffer and copy str_a's content into it. An associated reference counter for the data is increased instead.
QString str_b=str_a;
qDebug() << str_b.constData(); // print out address of data buffer, it is the same as for str_a
// str_a notices that the reference counter to its current shared data is >1, therefore it can't copy assign "Quisque..." directly into the buffer. Rather a new memory buffer is allocated, the new text copied there and the reference count to the "Lorem ipsum..."-string is decreased by one.

str_a="Quisque mollis elit sed vehicula luctus.";
qDebug() << str_a.constData(); // now a new address
qDebug() << str_b.constData(); // same as for the initial printout