C#中的“T”是什么意思？
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What does "T" mean in C#?
提问by Jim
I have a VB background and I'm converting to C# for my new job. I'm also trying to get better at .NET in general. I've seen the keyword "T" used a lot in samples people post. What does the "T" mean in C#? For example:
我有 VB 背景，我正在为我的新工作转换为 C#。总的来说，我也在努力在 .NET 方面变得更好。我已经看到人们发布的样本中经常使用关键字“T”。C#中的“T”是什么意思？例如：
public class SomeBase<T> where T : SomeBase<T>, new()
What does Tdo? Why would I want to use it?
有什么作用T？我为什么要使用它？
采纳答案by user39603
It's a symbol for a generic type parameter. It could just as well be something else, for example:
它是泛型类型参数的符号。它也可以是其他东西，例如：
public class SomeBase<GenericThingy> where GenericThingy : SomeBase<GenericThingy>, new()
Only T is the default one used and encouraged by Microsoft.
只有 T 是 Microsoft 使用和鼓励的默认值。
回答by Otávio Décio
It means "any class". It could be "B", "A", whatever. I think T is used because of "Template"
它的意思是“任何类”。它可以是“B”，“A”，随便什么。我认为使用 T 是因为“模板”
回答by Rob Walker
T is not a keyword per-se but a placeholder for a generic type. See Microsoft's Introduction to Generics
T 本身不是关键字，而是泛型类型的占位符。请参阅 Microsoft 的泛型简介
The equivalent VB.Net syntax would be:
等效的 VB.Net 语法是：
Public Class SomeBase(Of T As {Class, New}))
回答by Yossi Dahan
Best way would be to get yourself familiar with "Generics", many resources on the web, here's one
最好的方法是让自己熟悉“泛型”，网上有很多资源，这是一个
T is not a keyword but a name, could be anything really as far as I know, but T is the convention (when only one type is needed, of coruse)
T 不是关键字而是名称，据我所知可以是任何东西，但 T 是约定（当只需要一种类型时，coruse）
回答by biozinc
A good example of another name used instead of T wouldbe the hash table classes, e.g.
使用另一个名称代替 T 的一个很好的例子would是哈希表类，例如
public class Dictionary<K,V> ...
Where Kstands for Key and Vfor value. I think Tstands for type.
其中K代表 Key 和Vvalue。我认为T代表类型。
You might have seen this around. If you can make the connection, it should be fairly helpful.
你可能已经看到了这一点。如果您可以建立联系，那应该会很有帮助。
回答by jason
The Tis the name for the type parameter in a generic class. It stands for "Type" but you could just as well call it "Alice."
该T是泛型类的类型参数的名称。它代表“类型”，但您也可以称其为“爱丽丝”。
You use generics to increase reusability in a type-safe manner without needlessly duplicating code. Thus, you do not need to write classes for ListOfIntegers, ListOfStrings, ListOfChars, ListOfPersonsand so on but can instead write a generic class List<T>and then instantiate objects of types List<Int32>, List<string>, List<char>and List<Person>. The compiler does the work for you.
您可以使用泛型以类型安全的方式提高可重用性，而无需不必要地重复代码。因此，你不需要写类ListOfIntegers，ListOfStrings，ListOfChars，ListOfPersons等等而是可以写一个通用类List<T>，然后实例的类型的对象List<Int32>，List<string>，List<char>和List<Person>。编译器为您完成工作。
回答by Vilx-
That would be a "Generic". As people have already mentioned, there is a Microsoft explanationof the concept. As for why the "T" - see this question.
那将是一个“通用”。正如人们已经提到的，微软对这个概念有一个解释。至于为什么是“T”——见这个问题。
In a nutshell, it allows you to create a class/method which is specialized to a specific type. A classical example is the System.Collections.Generic.List<T>class. It's the same as System.Collections.ArrayList, except that it allows you to store only item of type T. This provides type safety - you can't (accidentally or otherwise) put items of the wrong type in your list. The System.Collections.Genericnamespace contains several other different collection types which make use of this.
简而言之，它允许您创建一个专用于特定类型的类/方法。一个经典的例子是System.Collections.Generic.List<T>类。它与 相同System.Collections.ArrayList，只是它允许您仅存储类型为 的项目T。这提供了类型安全性 - 您不能（意外或以其他方式）将错误类型的项目放入列表中。该System.Collections.Generic命名空间包含几个不同的集合类型，其利用了这一点。
As for where you could use it - that's up to you. There are many use-cases which come up from time to time. Mostly it's some kind of a self-made collection (when the builtin ones don't suffice), but it could really be anything.
至于你可以在哪里使用它 - 这取决于你。有许多用例不时出现。大多数情况下，它是某种自制的集合（当内置集合不够用时），但它真的可以是任何东西。
