如何使用2个键值创建地图

Question

I am looking for something like a school time table. Based on two input - Day of the week and Time of the day, one decides the subject. To implement this in c++, I was thinking of something like "map < pair < int, int>, int>". I was reading here to use a key class and operator overloading. Is there any other elegant way of doing it?

Thanks in Advance

Answer 1

That's not a map with two keys (which would allow you to look up items from knowledge of just one key), it's a composite key, and map<pair<day, time>, subject> should work just fine.

Also consider map<day, map<time, subject>> .

Answer 2

You could typedef it.

typedef pair<int, int> key;
map<key, int> myMap = new map<key, int>();

Answer 3

You can't create a map with 2 key values, you can create a map with a complex key value (composed of two types). However, this won't let you look at the map for say just day of week regardless of time of day. I would create a new class to use as key, and some helper functions to be able to work by just day or just time.

Also, for your use case Boost.MultiIndex may help you.