检查存在于两个集合中的任何元素 [英] Check for any element that exists in two collections

问题描述

我想知道 Linq 是否有一种方法可以检查两个集合是否至少有一个共同的元素.我希望是这样的:

I'm wondering if Linq has a method to check if two collections have at least a single element in common. I would expect something like this:

var listA = new List<int>() { some numbers };
var listB = new List<int>() { some numbers, potentially also in list A };

bool hasSameElements = listA.hasMatchingElements(listB);

它是否存在于 Linq 中，或者我应该为它编写自定义方法吗?

Does it exists in Linq or should I write a custom method for it?

我知道 Intersect 方法，但这不会产生整个交集吗?我只对检查两个集合是否相交感兴趣，生成整个集合似乎是一种浪费，尤其是在较大的集合中.

I am aware of the Intersect method, but doesn't this yield the entire intersection set? I'm only interested in checking IF the two collection intersect, yielding the entire set seems like a waste, especially on larger collections.

推荐答案

听起来就像你想要的:

bool hasSameElements = listA.Intersect(listB).Any();

如评论中所述，Intersect 使用惰性求值.它推迟所有执行，直到从结果中读取第一个元素；在这一点上，它会将 listB 的 all 加载到一个集合中，然后流式传输 listA 直到找到要产生的结果.那时，Any() 将返回 true，因此不会再做任何工作.请参阅我的 Edulinq发布在 Intersect 上以获取更多信息.

As noted in comments, Intersect uses lazy evaluation. It defers all execution until the first element is read from the result; at that point it will load all of listB into a set, and then stream listA until it finds a result to yield. At that point, Any() will return true and so no more work will be done. See my Edulinq post on Intersect for more information.

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