将元素存储在 unordered_set 中与将它们存储在 unordered_map 中
假设我有以下 User 结构：
struct User {
string userId;
UserType userType; // UserType is just an enumeration
string hostName;
string ipAddress;
//and more other attributes will be added here
};
并且我需要存储用户记录的集合（大约 10^5 个用户，也可以扩展到更高）。如果我将其存储为 unordered_set 或 unordered_map 性能会更好吗？ Unordered_set 在技术上与 HashSet 相同，unordered_map 与 HashMap 相同，对吗？使用常规集（有序）不是一个选择，因为当元素数量增加时插入和删除会变得非常慢。
unordered_set <User> userRecords;
或者
unordered_map <string, User> userRecords; // string is the user ID.
我需要它在插入、删除以及通过其 userId 访问特定用户对象方面非常快。
Suppose I have the following User struct:
struct User {
string userId;
UserType userType; // UserType is just an enumeration
string hostName;
string ipAddress;
//and more other attributes will be added here
};
and I need to store a collection of user records (around 10^5 users, can scale higher too ). Would it be better in performance if I store it as an unordered_set or unordered_map? Unordered_set is technically the same as HashSet, and unordered_map is the same as HashMap, right? Using a regular set (ordered) is not an option, as insertion and deletion will get very slow when the number of elements increase.
unordered_set <User> userRecords;
OR
unordered_map <string, User> userRecords; // string is the user ID.
I need it to be very fast in terms of insertion, deletion, and to access a particular user object by its userId.
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（3）
我会选择
unordered_map，因为我可以随时给定用户 ID 来获取用户，而无需任何额外的工作，而使用unordered_set我没有此功能。至于上述操作，速度几乎是一样的。
I would choose
unordered_map, because I can get a user, given a userid at any time, without any extra work, while withunordered_setI don't have this facility.As for the mentioned operations, the speed will be almost same.
由于
unordered_set<>无法让您通过 userId 轻松访问用户，因此unordered_map<>似乎是正确的选择。Since the
unordered_set<>doesn't give you the possibility to easily access a user by his userId,unordered_map<>seems to be the correct choice.如果性能是一个重要问题，那么您可能需要分析并查看哪一个性能更好。否则，请选择最符合逻辑地描述您想要做的事情的一项。 [只有 100K 个项目，如果您需要在其他地方订购，我认为
set和map可能具有可接受的性能]If performance is a significant concern then you'll probably want to profile and see which one performs better. Otherwise, choose the one that most logically describes what you're trying to do. [With only 100K items I think
setandmapmay yet have acceptable performance if you need ordering somewhere else]