IEnumerable选择 [英] IEnumerable Select

问题描述

有人可以解释为什么C#的下一行与下面的foeach块的行为不同吗?

Can someone explain why the following line of C# doesn't behave the same as the following foeach block?

string [] strs = {"asdf", "asd2", "asdf2"};
strs.Select(str => doSomething(str));


foreach(string str in strs){
  doSomething(str);
}

我在doSomething()中放置了一个断点，它在Select中不触发，但它与foreach一样.

I put a breakpoint inside of doSomething() and it doesn't fire in the Select but it does with the foreach.

TIA

推荐答案

在使用ToList()，ToArray()等将其转换为Enumarable之前，不会处理Linq查询.

The Linq query won't be processed until you convert it to an Enumarable using ToList(), ToArray(), etc.

顺便说一句，与您的foreach语句等效的是这样的:

And by the way the equivalent to your foreach statement is something like this:

strs.ForEach(doSomething);

strs.ToList().ForEach(doSomething);

或

Array.ForEach(strs, doSomething);

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