按照什么顺序做了C＃for each循环遍历目录＆LT; T＆GT ;? [英] In what order does a C# for each loop iterate over a List<T>?

问题描述

我想知道，在C＃中的foreach循环遍历顺序 System.Collections.Generic.List＆LT; T＆GT; 对象

I was wondering about the order that a foreach loop in C# loops through a System.Collections.Generic.List<T> object.

我发现<一个href=\"http://stackoverflow.com/questions/678162/sort-order-when-using-foreach-on-an-array-list-etc\">another关于同一主题的问题，但我不认为它回答我的问题让我满意的。

I found another question about the same topic, but I do not feel that it answers my question to my satisfaction.

有人指出，没有订单被定义。但作为其他人的状态，它横穿阵列的顺序是固定的（从0到长度-1）。 8.8.4 foreach语句

Someone states that no order is defined. But as someone else states, the order it traverses an array is fixed (from 0 to Length-1). 8.8.4 The foreach statement

也有人说，同样适用于任何标准班用命令（例如列表＆LT; T＆GT; ）。我找不到任何文件来支持这件事。因此，对于所有我知道它可能工作一样，现在，但也许在未来的.NET版本会有所不同（尽管它可能是不可能的）。

It was also said that the same holds for any standard classes with an order (e.g. List<T>). I can not find any documentation to back that up. So for all I know it might work like that now, but maybe in the next .NET version it will be different (even though it might be unlikely).

我也看了看 列表（T）.Enumerator 文档没有运气。

I have also looked at the List(t).Enumerator documentation without luck.

另一个相关的问题指出，对于Java，它是专门提及文档：

Another related question states that for Java, it is specifically mentioned in the documentation:

List.iterator（）在返回的元素的迭代器在此列表
  以正确的顺序。

List.iterator()returns an iterator over the elements in this list in proper sequence."

我要寻找的C＃文档中类似的东西。

I am looking for something like that in the C# documentation.

先谢谢了。

编辑：谢谢你为所有的答案（我惊人的速度有多快了那么多的回复）。我从所有的答案不解的是，列表＆LT; T＆GT; 并一直在其索引的顺序进行迭代。但我还是想看到的文档清晰的说明和平这一点，类似的在列表Java文档 。

Thank you for all you for all your answers (amazing how fast I got so many replies). What I understand from all the answers is that List<T> does always iterate in the order of its indexing. But I still would like to see a clear peace of documentation stating this, similar to the Java documentation on List.

推荐答案

基本上它是到的IEnumerator 实施 - 但对于一个列表＆LT; T＆GT ; 它总是会走在了名单的自然顺序，即相同的顺序索引：列表[0] ，列表[1] ，列表[2] 等。

Basically it's up to the IEnumerator implementation - but for a List<T> it will always go in the natural order of the list, i.e. the same order as the indexer: list[0], list[1], list[2] etc.

我不相信它的明确记载 - 至少，我还没有发现这样的文件 - 但我认为你可以把它当作保证。该订货的任何变化将毫无意义的突破各种code的。事实上，我很惊讶地看到的任何实现的IList＆LT; T＆GT; 这违背了这一点。诚然，这将是很高兴看到它专门记录...

I don't believe it's explicitly documented - at least, I haven't found such documentation - but I think you can treat it as guaranteed. Any change to that ordering would pointlessly break all kinds of code. In fact, I'd be surprised to see any implementation of IList<T> which disobeyed this. Admittedly it would be nice to see it specifically documented...

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