（）=>是什么？在C＃中意味着什么？ [英] What does () => mean in C#?

问题描述

我一直在阅读 Moq 的源代码，以下单元测试：

I've been reading through the source code for Moq and I came across the following unit test:

Assert.Throws<ArgumentOutOfRangeException>(() => Times.AtLeast(0));

在我的一生中，我不记得（）=>的实际作用。我认为这与匿名方法或Lambda有关。而且我确定我知道它的作用，此刻我不记得了...。

And for the life of me, I can't remember what () => actually does. I'm think it has something to do with anonymous methods or lambdas. And I'm sure I know what it does, I just can't remember at the moment....

并使情况更糟.... Google并没有太大帮助和 stackoverflow都不是

And to make matters worse....google isn't being much help and neither is stackoverflow

有人可以给我一个非常愚蠢的问题的快速答案吗？

Can someone give me a quick answer to a pretty noobish question?

推荐答案

（）=>是一个无效的lambda表达式。它表示传递给assert的匿名函数。抛出，并在该函数内部调用。

()=> is a nullary lambda expression. it represents an anonymous function that's passed to assert.Throws, and is called somewhere inside of that function.

void DoThisTwice(Action a) { 
    a();
    a();
}
Action printHello = () => Console.Write("Hello ");
DoThisTwice(printHello);

// prints "Hello Hello "

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