QHash operator+ is deprecated

Cocojambo

Hi. Is there any alternative variant instead of that deprecated? It works correctly but just want to get rid of this intrusive message in correct way (without disabling notice messages).

QHash<QString, QString> list;
QHash<QString, QString>::iterator iterator = list.begin();
iterator += 10; // <- Notice: 'operator+' is deprecated

sierdzio

Call iterator.next() 10 times, or call iterator.findNext() if you can search for the next item.

Cocojambo

@sierdzio
Well ... it's quiet questionable solution to call iterator ten times in empty loop :)
I use it for getting random item from the list. So "10" can be any value < list.size().
And findNext() in my case is useless.

jsulm

@Cocojambo Call https://doc.qt.io/qt-5/qhash.html#keys to get a QList with the keys and then use random number to access random key and use it to get the value.

sierdzio

Keys in QHash are already stored semi-randomly. So there's probably no need to use a random number when accessing at all.

Bonnie

@Cocojambo
The original operator+= does exactly the same thing (call ++ 10 time when you write += 10), you just cannot see that...
It's like

int j = 10; //the value you pass to it
while(j--) ++iterator;

And according to the doc

This operator is deprecated in order to align with std::unordered_map functionality.

So I think there won't be any alternative function to replace it.

Cocojambo

@sierdzio
But we will get the same "random" element if we call it several times (if QHash wasn't changed).

@jsulm was thinking about it but it should be slower. Needs to test)

@Bonnie Thanks, it makes sense.

sierdzio

@Cocojambo said in QHash operator+ is deprecated:

But we will get the same "random" element if we call it several times (if QHash wasn't changed).

Simply take the next index each time you need a "random" element. My point is that there is (probably) no need to randomize the index. All depends on how really random you need your result to be.