如果是值类型/引用类型约束在C＃有用吗？ [英] When is a value type / reference type constraint useful in C#?

问题描述

我在找当值类型/引用类型约束是有用的演示简单的例子。

I'm looking for simple examples that demonstrate when the value type / reference type constraints are useful.

... where T : struct  // when is this useful?
... where T : class   // and what about this?

我记得看到一些非常好的例子，在过去，但我无法找到他们。

I remember seeing some very nice examples in the past but I just can't find them.

推荐答案

它允许您使用为运营商对T，如果它是 T：类

It allows you to use as operator on T if it is T:class.

它禁止你与空如果T T：结构

请注意，如果你省略 T：类，那么你可以比较T可空，即使T是值类型

Note that if you omit T:class then you can compare T to null even when T is a value type.

[注：我需要前几次编辑这个职位它得到正确的。至少我希望它现在是正确的。]

[Note: I needed to edit this post a few times before it got correct. At least I hope it is now correct.]

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