当正则表达式被@符号包围时，这是什么意思? [英] What does it mean when a regular expression is surrounded by @ symbols?

问题描述

问题

当正则表达式被@符号包围时，这是什么意思?这是否意味着与被斜杠包围不一样? @x或@i何时结束呢?现在，我想一想，周围的斜线甚至意味着什么?

What does it mean when a regular expression is surrounded by @ symbols? Does that mean something different than being surround by slashes? What about when @x or @i are on the end? Now that I think about it, what do the surrounding slashes even mean?

背景

我看到了John发表的 StackOverflow答案 Kugelman，在那里他表现出认真的Regex技能.

I saw this StackOverflow answer, posted by John Kugelman, in which he displays serious Regex skills.

现在，我已经习惯于看到正则表达式被斜线包围

Now, I'm used to seeing regexes surrounded by slashes as in

/^abc/

但是他使用了用@符号包围的正则表达式:

But he used a regex surrounded by @ symbols:

'@
        ^%
        (.{2})          # State, 2 chars
        ([^^]{0,12}.)   # City, 13 chars, delimited by ^
        ([^^]{0,34}.)   # Name, 35 chars, delimited by ^
        ([^^]{0,28}.)   # Address, 29 chars, delimited by ^
        \?$
 @x'

实际上，它似乎采用以下格式:

In fact, it seems to be in the format:

@^abc@x

在尝试搜索google的含义的过程中(这对google来说是个难题)，我还看到了以下格式:

In the process of trying to google what that means (it's a tough question to google!), I also saw the format:

@^abc@i

很明显 x 和 i 是不匹配的字符.

It's clear the x and the i are not matched characters.

那是什么意思?

在此先感谢您的回复，

-gMale

推荐答案

周围的斜杠只是正则表达式分隔符.您可以使用任何字符(afaik)来执行此操作-最常用的是/，我见过的其他常用的是#

The surrounding slashes are just the regex delimiters. You can use any character (afaik) to do that - the most commonly used is the /, other I've seen somewhat commonly used is #

换句话说，@whatever@i本质上与/whatever/i相同(i是不区分大小写的匹配项的修饰符)

So in other words, @whatever@i is essentially the same as /whatever/i (i is modifier for a case-insensitive match)

您可能要使用/以外的其他原因是如果您的正则表达式包含字符.您避免逃脱它，类似于使用''代替字符串".

The reason you might want to use something else than the / is if your regex contains the character. You avoid having to escape it, similar to using '' for strings instead of "".

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