loop QHash by insert order

Question

Is it possible to loop a QHash by the insert order? The method below seem to loop the hash by some other factor:

QHashIterator<QString, QString> i(hash);
while (i.hasNext()) {
    i.next();
    qDebug() << i.key() << ": " << i.value();
}

EDIT:

I figured it was impossible with QHash but what should I use instead?

If you want to iterate over insert order, why don't you use a QList? — mbx, Aug 29 '11 at 09:54

score 13 · Accepted Answer · edited Feb 07 '18 at 21:21

13

From QHash documentation,

QHash is unordered, so an iterator's sequence cannot be assumed to be predictable. If ordering by key is required, use a QMap

So it is not possible.

If you want ordering based on the keys, use QMap instead..

Hope it helps..

Edit:

If you don't need Key and Value Logical mapping and just their values, you can use

QList<QPair<QString,QString>> pairs;

For e.g:

The first value can be obtained by

QString firstValue = pairs.at(0).first;

Similarly for the second value in the QPair,

QString secondValue = pairs.at(0).second;

And you can iterate over the QList to retrieve the elements in the inserted order..

edited Feb 07 '18 at 21:21

Random Citizen

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answered Aug 04 '10 at 12:13

liaK

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Thanks, but I want to order the hash from the insert time not the key. – Dennis Aug 04 '10 at 17:25
In that case, **it is not possible**. – liaK Aug 04 '10 at 17:54

score 1 · Answer 2 · answered Aug 04 '10 at 11:26

1

QHash doesn't remember your insert order. It is designed for fast random access. The order you get with the iterator is arbitrary.

answered Aug 04 '10 at 11:26

deinst

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score 0 · Answer 3 · answered Aug 04 '10 at 11:34

0

If you only insert elements (no element removal) in the QHash you could use an array/list in parallel. It is not a very elegant solution but what you want cannot be achieved with QHash container only.

answered Aug 04 '10 at 11:34

INS

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loop QHash by insert order

3 Answers3