什么时候应该使用HashSet的＆LT; T＆GT;类型？ [英] When should I use the HashSet<T> type?

问题描述

我探索的HashSet＆LT; T＆GT; 的类型，但我不明白的地方矗立在集合

I am exploring the HashSet<T> type, but I don't understand where it stands in collections.

你可以使用它来替换名单，其中，T＆GT; ？我想象的性能的HashSet＆LT; T＆GT; 会更好，但我看不出个人访问它的元素

Can one use it to replace a List<T>? I imagine the performance of a HashSet<T> to be better, but I couldn't see individual access to its elements.

难道只为枚举？

推荐答案

有关的重要的事情的HashSet＆LT; T＆GT; 是正确的，在这个名字：这是一个的设置的。唯一的东西，你可以用一组做的是确定哪些其成员，并检查项目是否是一个成员。

The important thing about HashSet<T> is right there in the name: it's a set. The only things you can do with a single set is to establish what its members are, and to check whether an item is a member.

询问是否可以检索一个元素（如设置[45] ）被误解集的概念。有没有这样的事情为一组的45元。在一组项目没有顺序。在集{1，2，3}和{2,3，1}是在各方面都相同的，因为它们具有相同的成员资格，并籍是最重要的。

Asking if you can retrieve a single element (e.g. set[45]) is misunderstanding the concept of the set. There's no such thing as the 45th element of a set. Items in a set have no ordering. The sets {1, 2, 3} and {2, 3, 1} are identical in every respect because they have the same membership, and membership is all that matters.

这有点危险的迭代一个的HashSet＆LT; T＆GT; ，因为这样做强加在集中的项目订单。该顺序是不是真正的组的一个属性。你不应该依赖于它。如果在集合中的项目顺序对你很重要，该集合不是一套。

It's somewhat dangerous to iterate over a HashSet<T> because doing so imposes an order on the items in the set. That order is not really a property of the set. You should not rely on it. If ordering of the items in a collection is important to you, that collection isn't a set.

设定实在有限，并具有独特的成员。而另一方面，他们是真快。

Sets are really limited and with unique members. On the other hand, they're really fast.

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