我用的是第三个，但在其他两个中，第一个似乎没那么奇怪。 string是string的别名，但在赋值中看到它们会让人感觉不舒服。

编译器应该让它们在长期运行时都是一样的。选择一个标准，这样你的代码就容易阅读，并坚持下去。

最好的代码是没有代码:

编码的基本性质是，作为程序员，我们的任务是认识到我们所做的每一个决定都是一种权衡。从简洁开始。根据测试的需要增加其他维度。

因此，代码越少越好:更喜欢“”而不是字符串。Empty或String.Empty。这两篇文章的篇幅长了六倍，但没有额外的好处——当然也没有额外的清晰度，因为它们表达的信息完全相同。

http://blogs.msdn.com/b/brada/archive/2003/04/22/49997.aspx:

As David implies, there difference between String.Empty and "" are pretty small, but there is a difference. "" actually creates an object, it will likely be pulled out of the string intern pool, but still... while String.Empty creates no object... so if you are really looking for ultimately in memory efficiency, I suggest String.Empty. However, you should keep in mind the difference is so trival you will like never see it in your code... As for System.String.Empty or string.Empty or String.Empty... my care level is low ;-)

虽然差别非常非常小，但差别仍然存在。

""在String时创建一个对象。空则不然。但是这个对象只创建一次，如果代码中有另一个""，就会从字符串池中引用它。 String和String是一样的，但是我建议使用String。空(以及字符串。格式字符串。因为点表示法表示的是类，而不是操作符，而且类以大写字母开头符合c#编码标准。

I strongly prefer String.Empty, aside from the other reasons to ensure you know what it is and that you have not accidentally removed the contents, but primarily for internationalization. If I see a string in quotes then I always have to wonder whether that is new code and it should be put into a string table. So every time code gets changed/reviewed you need to look for "something in quotes" and yes you can filter out the empty strings but I tell people it is good practice to never put strings in quotes unless you know it won't get localized.