<![CDATA[Allocating memory in Desctructor for deleting QHash values]]>Hello ! :)

is there a QHash method which returns one key or its hashed value (as a reference)?

I attempt to delete objects stored as values in a QHash in the Destructor of a class of mine.

I only found the method keys() to get all keys of the hash which requires allocating a QList, or don't I have to allocate a QList?

If the keys() method fails due to memory constraints, I can't destruct my class, (because I don't get the keys which I need to find the values to delete) or can I ?

Or is there an other approach to this kind of destructing?

Thank you for your attempt and Best Regards!

]]>https://forum.qt.io/topic/28431/allocating-memory-in-desctructor-for-deleting-qhash-valuesRSS for NodeThu, 23 Apr 2026 07:55:56 GMTTue, 18 Jun 2013 15:21:43 GMT60<![CDATA[Reply to Allocating memory in Desctructor for deleting QHash values on Tue, 18 Jun 2013 15:50:57 GMT]]>I'm not sure. Probably it's already allocated when you create the hash. Take a look at the code if you are so inclined, or use a profiler to see what happens at runtime.

"QObject":http://qt-project.org/doc/qt-4.8/metaobjects.html stuff is here. It does introduce overhead, so if your device is low on memory and you have a lot of objects to create, then maybe it's not a good idea.

]]>https://forum.qt.io/post/183309https://forum.qt.io/post/183309Tue, 18 Jun 2013 15:50:57 GMT<![CDATA[Reply to Allocating memory in Desctructor for deleting QHash values on Tue, 18 Jun 2013 15:46:05 GMT]]>Yes, I read that. Does creating the QHashIterator not allocate memory?
The values are of a custom-made class. Can I read up on the benefit of deriving of QObject somewhere? Where?
Thank you.

]]>https://forum.qt.io/post/183307https://forum.qt.io/post/183307Tue, 18 Jun 2013 15:46:05 GMT<![CDATA[Reply to Allocating memory in Desctructor for deleting QHash values on Tue, 18 Jun 2013 15:39:37 GMT]]>You can go thorough all values with:
@
QHashIterator<QString, int> i(hash);
while (i.hasNext()) {
i.next();
cout << i.key() << ": " << i.value() << endl;
}
@

As mentioned in - surprise! - "official documentation":http://qt-project.org/doc/qt-5.0/qtcore/qhash.html. Also, remember that if your values are QObject pointers that are properly parented, you don't need to delete them, Qt will do it for you.

]]>https://forum.qt.io/post/183304https://forum.qt.io/post/183304Tue, 18 Jun 2013 15:39:37 GMT