从Dictionary< string，string>获取第一个键. [英] Get first key from Dictionary<string, string>

问题描述

我正在使用 System.Collections.Generic.Dictionary< string，string> .

我想从这本字典中返回第一个键.我尝试了 dic.Keys [0] ，但是我对 Keys 属性(这是一个 KeyCollection 对象)唯一拥有的是枚举器.

I want to return the first key from this dictionary. I tried dic.Keys[0] but the only thing I have on the Keys property (which is a KeyCollection object) is an enumerator.

我是否必须枚举所有键才能得到第一个?

Do I have to enumerate through all the keys to get the first one?

推荐答案

假设您使用的是.NET 3.5:

Assuming you're using .NET 3.5:

dic.Keys.First();

请注意，在字典中没有迭代顺序可以保证键/值对的顺序.您可能会发现，在很多情况下，您会弄出放入字典中的第一把钥匙-但您绝对绝对不能依靠它.正如Skirwan所说，实际上并没有第一"的概念.从本质上讲，以上内容将为您提供词典中的键"-这就是所保证的一切.

Note that there's no guaranteed order in which key/value pairs will be iterated over in a dictionary. You may well find that in lots of cases you get out the first key that you put into the dictionaries - but you absolutely must not rely on that. As Skirwan says, there isn't really a notion of "first". Essentially the above will give you "a key from the dictionary" - that's about all that's guaranteed.

(如果您不知道字典是否为空，则可以使用 FirstOrDefault .)

(If you don't know whether the dictionary is empty or not, you could use FirstOrDefault.)

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