局部变量设置为零?(目标-C) [英] Local variables set to nil? (Objective-C)

问题描述

我正在读一本关于 Objective-C 的书，作者说如果局部变量没有赋值，它们将被设置为 nil，但静态变量将被设置为零.所以，我设置了 int a 并且没有给它赋值.然后 NSLog(@"%i", a) 显示它并且 a 显示为零.我对此有点困惑，我想知道是否有人可以为我澄清一下?

I'm reading a book on Objective-C and the author said that if local variables aren't assigned a value they will be set to nil, but static variables will be set to zero. So, I set up int a and didn't assign it a value. Then NSLog(@"%i", a) to display it and a was displayed as zero. I was a little confused on that and I was wondering if someone could clarify it for me?

推荐答案

启用 ARC 后，无论您在何处创建它们，Objective-C 对象指针变量都将设置为 nil.

With ARC enabled, your Objective-C object pointer variables will be set to nil regardless of where you create them.

如果没有 ARC，对于内置的 C 类型，您的变量将不会被初始化.

Without ARC, and for built in C types, your variables will not be initialized.

在分配对象时，Objective-C 对象的实例变量始终设置为 0(或 nil).

Instance variables of Objective-C objects are always set to 0 (or nil) when you allocate an object.

静态设置为 0.

不过，我已经养成了总是给变量一个默认值的习惯.这是一个好习惯.

I've gotten in the habit of always giving a default value to variables, though. It's been a good habit to have.

这篇关于局部变量设置为零?(目标-C)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！