问题描述
该方法通过yield return语句返回的IEnumerable
The method returns IEnumerable via a yield return statement.
如果从未出现yield语句（它的内部条件逻辑），将方法返回null，或者将它0的计数返回一个可枚举？
If the yield statement never occurs (it's inside conditional logic), will the method return null, or will it return an Enumerable with a count of 0?
推荐答案
一个有效的IEnumerable当你遍历它不产生价值。
A valid IEnumerable that produces no values when you iterate through it.
试想一下：您可以将IEnumerable的发生器存储在一个变量 - 代码本身当你真正遍历这些结果只是得到执行。你怎么可以，如果你有执行的代码空？或者，你是怎么知道的功能，不运行它不会产生任何东西。
Just think of it: You can store the IEnumerable generator in a variable - the code itself just gets executed when you actually iterate through the results. How could you execute the code if you had null? Or how did you know the function doesn't yield anything without running it.
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