Do I need to delete QObjects?

Bob Asm

Do I need to delete explicitly QObjects like in below code or Qt take care of that memory mangement by itself?

void myClass:startTimer() {
  auto timer = new QTimer(this);
  timer->setInterval(1000*5);
   timer->setSingleShot(true);
  bool ok = connect(timer,  &QTtimer::timeout, [=]() {  loop->quit(); });
 assert(ok);
 timer->start();
 // do something 
 loop->quit();
}

mrjj

Hi
When you assign a parent, you should not delete it manually. Parent will
new QTimer(this); << this is owner.
http://doc.qt.io/qt-5/objecttrees.html

SGaist

Hi,

The timer object will get automatically delete when its parent also is but the way you do it, you'll be filling up memory with QTimer objects each time you call your startTimer function. So either delete it explicitly at the end of the method or use a stack variable.

VRonin

An alternative is to connect(timer, &QTimer::timeout,timer, &QTimer::deleteLater);

P.S.
You don't need to assert the return of connect when you use Qt5 connect syntax, the compiler will "static assert" it for you

JKSH

For this particular example, you don't need to create a QTimer object at all, so there is nothing to delete. Just use the static function, QTimer::singleShot().

Your 6 lines of code can be reduced to 1 line:

    QTimer::singleShot(  1000*5,  [=]{ loop->quit(); }  );