C# 为什么存在小写和大写版本的字符串，我应该使用哪个？
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Why do lowercase and uppercase versions of string exist and which should I use?
提问by BenAlabaster
Okay, this may be a dumb question, but I've not been able to find any information on it.
好吧，这可能是一个愚蠢的问题，但我找不到任何相关信息。
Are String.Empty and string.Empty the same? I always find myself gravitating towards using the upper case version (String.Empty) because I prefer the color and look of it in my IDE than the lower case version (string.Empty)...
String.Empty 和 string.Empty 是一样的吗？我总是发现自己倾向于使用大写版本 (String.Empty)，因为与小写版本 (string.Empty) 相比，我更喜欢它在 IDE 中的颜色和外观……
Is there a "correct" way to use these that differ or is it entirely down to personal preference? It was my assumption that they're both the same, but to be honest, I never gave it any thought until for whatever reason today I wondered "If they both exist, they must both exist for a reason".
是否有一种“正确”的方式来使用这些不同的东西，还是完全取决于个人喜好？我假设它们是相同的，但老实说，直到今天出于某种原因我想知道“如果它们都存在，它们都必须存在一定的原因”之前，我从来没有考虑过。
Isthere a reason that anyone knows of? If so, what is it? Can anyone enlighten me?
是否有一个原因，任何人都知道？如果是，那是什么？任何人都可以启发我吗？
P.S. The "exact duplicates" only answer half of the question - "which is right?", not the "why do they both exist?"
PS“完全重复”只能回答问题的一半——“哪个是对的？”，而不是“为什么它们都存在？”
Exact Duplicate: What is the difference between String and string in C#?
完全重复：C# 中的字符串和字符串有什么区别？
Exact Duplicate: String vs string in C#
完全重复：C# 中的字符串与字符串
采纳答案by Konrad Rudolph
In C#, lower-case type names are aliases for the System.xxxtype names, e.g. stringequals System.Stringand intequals System.Int32.
在 C# 中，小写类型名称是类型名称的别名System.xxx，例如stringequalsSystem.String和intequals System.Int32。
It's best practice to use these language aliases for the type names instead of their framework equivalent, for the sake of consistency. So you're doing it wrong. ;-)
为了保持一致性，最佳实践是将这些语言别名用于类型名称而不是它们的框架等效项。所以你做错了。;-)
As for a reason why they both exist, the .NET types exist because they are defined in a language-independent standard for the .NET libraries called CTS (common type system). Why C# defines these aliases is beyond me (VB does something quite similar). I guess the two reasons are
至于它们都存在的原因，.NET 类型之所以存在，是因为它们是在称为 CTS（通用类型系统）的 .NET 库的独立语言标准中定义的。为什么 C# 定义这些别名超出了我的理解（VB 做了一些非常相似的事情）。我想这两个原因是
- Habit. Get all these C and Java programmers to use C# by providing the same type names for some fundamental types.
- Laziness: You don't have to import the
Systemnamespace to use them.
- 习惯。通过为一些基本类型提供相同的类型名称，让所有这些 C 和 Java 程序员使用 C#。
- 懒惰：您不必导入
System命名空间即可使用它们。
EDITSince many people seem to prefer the other notation let me point out that this is by no means unreasonable. A good case can actually be made for the usage of the CTS type names rather than C#'s keywords and some superficially good arguments are offered in the other answers. From a purity/style point of view I would probably concur.
编辑由于许多人似乎更喜欢其他符号，让我指出这绝不是不合理的。实际上可以为使用 CTS 类型名称而不是 C# 的关键字制作一个很好的案例，其他答案中提供了一些表面上很好的论据。从纯度/风格的角度来看，我可能会同意。
However, consider if this is worth breaking a well-established convention that helps to unify code across projects.
但是，请考虑这是否值得打破有助于跨项目统一代码的完善约定。
回答by Ed S.
It is conceptually similar to something like this:
它在概念上类似于以下内容：
using int=System.Int32
回答by Frederik Gheysels
string is mapped to the String class AFAIK, so they're the same.
string 映射到 String 类 AFAIK，因此它们是相同的。
The same is true for, for example int and Int32.
例如 int 和 Int32 也是如此。
回答by Arjan Einbu
They are both the same.
他们都是一样的。
Personally I prefer using the lowercase string, the "blue one", using the C# keyword instead of the .NET class name for the same reason I'm using int instead of Int32. Also, the lowercased one doesn't require inclusion of the System namespace...
我个人更喜欢使用小写字符串“蓝色字符串”，使用 C# 关键字而不是 .NET 类名，原因与我使用 int 而不是 Int32 的原因相同。此外，小写的不需要包含 System 命名空间...
回答by Shalmanese
Personally, I prefer to use String as both String and Object are references whereas all the other base types are value types. In my mind, that's the clearest separation.
就个人而言，我更喜欢使用 String，因为 String 和 Object 都是引用，而所有其他基本类型都是值类型。在我看来，这是最清晰的分离。
