Objective-C 中的 bool、Boolean 和 BOOL 之间有什么区别吗? [英] Is there any difference between bool, Boolean, and BOOL in Objective-C?

问题描述

我知道 BOOL 实际上是有符号字符的 typedef，但是 Boolean 呢?

bool、Boolean 和 BOOL 有什么区别?

解决方案

Boolean 是一个旧的 Carbon 关键字(历史 Mac 类型)，定义为 unsigned char.BOOL 是一种Objective-C 类型，定义为signed char.bool 是 _Bool 标准 C 类型的定义版本.它被定义为一个int.使用 BOOL.

编辑(2019 年):Apple 在一些 BOOL 的底层实现">新文档.基本上，在 macOS 上，BOOL 最终还是一个 signed char，但在 iOS 和相关平台上，它是一个原生的 C bool 下面.p>

I know BOOL is actually a typedef of signed char, but what about Boolean?

What is the difference between bool, Boolean and BOOL?

解决方案

Boolean is an old Carbon keyword (historic Mac type), defined as an unsigned char. BOOL is an Objective-C type defined as signed char. bool is a defined version of the _Bool standard C type. It's defined as an int. Use BOOL.

Edit (2019): Apple talks about the underlying implementation of BOOL in some new documentation. Basically, on macOS, BOOL is still ultimately a signed char, but on iOS and related platforms, it a native C bool underneath.

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