问题
I need structure like QMap but without sorting on keys, so if I insert item there first I can count that this item will be before all others. And insert pair before or after specified element. Does Qt have such?
回答1:
QMap is implemented as a tree, which means that the insertion order does not matter. It appears that you are looking for a queue. However, if you need a container which can be iterated in both insertion order and at the same time accessed through a specific key, then Qt has no such structure for you.
These could help you:
- A std::map that keep track of the order of insertion?
- Make Map Key Sorted According To Insert Sequence
回答2:
I use a
QList<QPair<key,value>>
to achieve this. But look up consumes more time as you will need to loop through the QList and use the QPair.first to look for the item you want.
edit: if you dont need it to interact with other API alot, you can use QVector to replace QList which is faster according to Qt official
来源：https://stackoverflow.com/questions/16101952/qmap-but-without-sorting-by-key