I have an std::unordered_map<MyStruct>. It's unordered for extra-fast lookups which is what will be needed most of the time. However, once, at startup, I'd like to iterate over it in order of MyStruct::myInt.
The container currently contains upwards of 2000 elements, and might reach as high as 5-10 thousand.
Is there some way I can iterate over it in an order other than its internal hashing order?
I'm not worried about speed.
No.
If you know the keys used you can sort them and then look up the items in order.
You could put them in a map and iterate over them (and use the map to fill the unordered_map) then throw the map away.
Alright, thanks.
I'm now using a temporary map of references:
std::map<Key, std::reference_wrapper<Value>> sortedMap(std::begin(unsortedMap), std::end(unsortedMap));
for(const auto &pair : sortedMap)
{ ... }I'm pretty sure boost::multi_index (http://www.boost.org/doc/libs/1_54_0/libs/multi_index/doc/index.html) can do what you're asking for. You can set up a sequential index and an unordered index.
I'm pretty sure boost::multi_index (http://www.boost.org/doc/libs/1_54_0/libs/multi_index/doc/index.html) can do what you're asking for. You can set up a sequential index and an unordered index.
