如何在不同的上下文中使用行首/行尾符号（^ 或 $）？
在做一些小的正则表达式任务时，我遇到了这个问题。我有一个字符串，它是一个标签列表，例如如下所示：foo,bar,qux,garp,wobble,thud
我需要做的是检查某个标签（例如“garp”）是否在此列表中。 （它最终匹配的内容并不重要，只要是否匹配即可。）
我的第一个也是有点愚蠢的尝试是使用以下正则表达式：[^,]garp[,$]
我的想法是，在 'garp' 之前应该有行/字符串的开头或逗号，在 'garp' 之后应该有逗号或行/字符串的末尾。
现在，很明显这个正则表达式是错误的：^ 和 $ 在字符类 [ ] 的上下文中都改变了它们的行为。
我最终想出的是以下内容：^garp$|^garp,|,garp,|,garp$
这个正则表达式只是一一处理这 4 种情况。 （标记在列表的开头、中间、末尾，或者作为列表的唯一元素。）最后一个正则表达式在我看来有点丑陋，只是为了好玩，我想让它变得有点丑陋更优雅。
有没有办法在字符类的上下文中使用行开头/行结尾字符（^ 和 $）？
编辑： 好的，希望有更多信息，所以这里是： 我在 Oracle SQL 语句中使用它。遗憾的是，这不允许任何环视断言，但因为我只感兴趣是否存在匹配（而不是匹配的内容），这并没有真正影响我。 标签可以包含非字母字符，例如 - 或 _，因此 \bgarp\b 不起作用。另外，正如 SilentGhost 所说，一个标签可以包含另一个标签，因此 /garp/ 也不起作用。
While doing some small regex task I came upon this problem. I have a string that is a list of tags that looks e.g like this:foo,bar,qux,garp,wobble,thud
What I needed to do was to check if a certain tag, e.g. 'garp' was in this list. (What it finally matches is not really important, just if there is a match or not.)
My first and a bit stupid try at this was to use the following regex:[^,]garp[,$]
My idea was that before 'garp' there should either be the start of the line/string or a comma, after 'garp' there should be either a comma or the end of the line/string.
Now, it is instantly obvious that this regex is wrong: Both ^ and $ change their behaviour in the context of the character class [ ].
What I finally came up with is the following:^garp$|^garp,|,garp,|,garp$
This regex just handles the 4 cases one by one. (Tag at beginning of list, in the center, at the end, or as the only element of the list.) The last regex is somehow a bit ugly in my eyes and just for funs sake I'd like to make it a bit more elegant.
Is there a way how the start of line/end of line characters (^ and $) can be used in the context of character classes?
EDIT:
Ok, some more info was wished so here it is:
I'm using this within an Oracle SQL statement. This sadly does not allow any look-around assertions but as I'm only interested if there is a match or not (and not what is matched) this does not really affect me here.
The tags can contain non-alphabetical characters like - or _ so \bgarp\b would not work. Also one tag can contain an other tag as SilentGhost said, so /garp/ doesnt work either.
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没有正则表达式：
Without regex:
您不能按照您希望的方式在字符类中使用
^和$- 它们将按字面解释，但您可以使用交替来实现相同的效果：You can't use
^and$in character classes in the way you wish - they will be interpreted literally, but you can use an alternation to achieve the same effect:您只需要使用字边界 (
\b) 而不是^和$：you just need to use word boundary (
\b) instead of^and$:只需使用环视来解决此问题：
环视和常规组的区别在于，对于常规组，逗号将成为匹配的一部分，而对于环视则不会。但在这种情况下，这没有什么区别。
Just use look-arounds to solve this:
The difference with look-arounds and just regular groups are that with regular groups the comma would be part of the match, and with look-arounds it wouldn't. In this case it doesn't make a difference though.