我们可以为 STL 映射中的键使用用户定义的类吗?
我需要地图中的一个键，但是，我发现它应该是多个数据.我可以将这些数据放在一个用户定义的类中，并将整个类作为映射中的键吗?
I need a key in the map, however, I found it should be multiple data. Can I put these data in one user defined class and put the whole class as a key in the map?
会影响时间效率吗?
此处还应考虑哪些其他问题?
What other concerns should be applied here?
推荐答案
任何类型都可以作为key使用
Any type can be used as a key as long as it is
- 可复制
- 可分配
- 具有可比性，因为地图是按键排序的
如果你的类只是一个简单的结构，那么它已经是可复制和可分配的.要使类具有可比较性，您必须实现 operator<，或者使用自定义比较函数创建映射以供替代.
If your class is just a simple structure, then it's already copyable and assignable. For a class to be comparable, you must either implement operator<, or create the map with a custom comparison function to use instead.
对时间效率的唯一影响来自较大的对象需要更长的时间来复制和比较.如果对象需要那么大，那么您无能为力，所以不用担心.
The only impact on time efficiency comes from larger objects taking longer to copy and compare. If the objects need to be that size, then there's nothing you can do about that, so don't worry about it.
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