Nullable< bool>的用途是什么?类型? [英] What is the use of Nullable<bool> type?

问题描述

bool 变量可以为true或false，而 bool?也可以为null.

a bool variable could hold true or false, while bool? could be null as well.

为什么我们需要bool的第三个值? 如果不是 true ，那就等于== false

Why would we need a third value for bool ? If it is not true, what ever it is, it is == false

您能提出一个我更喜欢布尔的情况吗?.

Can you suggest a scenario where I would fancy a bool? instead.

谢谢

推荐答案

出于多种原因，某些事情可能是正确的，错误的或不确定的.一个人怎么回答你的第三个孩子是女孩吗?"如果一个人只有两个孩子?正确和错误均不正确.如果说比较不适用，则以Null为宜.

Something can be true, false or undefined for many reasons. How would one answer "Is your third child a girl?" if one only has two children? Both true and false are incorrect. Null would be appropriate as saying that the comparison doesn't apply.

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