是什么和<<意思是? [英] What does | and << mean?

问题描述

很抱歉，如果这是一个常见问题，但是我不知道它叫什么，所以我在搜索它时遇到了麻烦.

Sorry if this is a common question but I don't know what it's called so I'm having trouble searching for it.

这是如何工作的:

view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

我知道这意味着视图可以同时获得灵活的宽度和高度，但是它如何存储这样的两个变量?

I understand that it means that the view gets both flexible width and height, but how does it store two variables like that?

如果我查看UIViewAutoresizing的typedef，它看起来像:

If i look at the typedef for UIViewAutoresizing it looks like:

enum {
    UIViewAutoresizingNone                 = 0,
    UIViewAutoresizingFlexibleLeftMargin   = 1 << 0,
    UIViewAutoresizingFlexibleWidth        = 1 << 1,
...

那么，这样一个变量如何存储一个以上的值?

So, how can one variable store more than one value like this?

推荐答案

"|"是按位或".

<<"也是按位操作转移.它将所有位向左移动:

"<<" is also a bitwise operation shifting. it moves all the bits to the left:

00100 << 1 = 01000

阅读 wiki ，您对或"和移位操作感兴趣.

Read the wiki, you're interested in "or" and shift operations.

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