php – 可变长度的正则表达式
发布时间：2020-12-13 17:17:07 所属栏目：PHP教程 来源：网络整理
导读：我的正则表达式如下： (?![s]*?("|quot;)")WORD(?![s]*?("|quot;)) 正如你所看到的,我试图匹配WORD的所有实例,除非它们在“引号”内.所以… WORD - Find this"WORD" - Don't find this" WORD " - Also don't find this,even though not touching against
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我的正则表达式如下：
(?<![s]*?("|")")WORD(?![s]*?("|"))
正如你所看到的,我试图匹配WORD的所有实例,除非它们在“引号”内.所以… WORD <- Find this "WORD" <- Don't find this " WORD " <- Also don't find this,even though not touching against marks "WORD" <- Dont find this (I check " and " so works after htmlspecialchars) 我相信我的正则表达式会完美地工作如果我没有收到错误： Compilation failed: lookbehind assertion is not fixed length 考虑到外观的局限性,有没有办法做我想做的事情？ 如果您能想到其他任何方式让我知道. 非常感谢, 马修 附： WORD部分实际上包含Jon Grubers URL检测器 解决方法
我建议采用不同的方法.只要引号被正确平衡,这将起作用,因为你知道你在引用的字符串中iff后面的引号数是奇数,从而使lookbehind部分不必要：
if (preg_match(
'/WORD # Match WORD
(?! # unless it's possible to match the following here:
(?: # a string of characters
(?!") # that contains neither "
[^"] # nor "
)* # (any length),("|") # followed by either " or " (remember which in 1)
(?: # Then match
(??1(?!1).)*1 # any string except our quote char(s),followed by that quote char(s)
(??2(?!1).)*1 # twice,)* # repeated any number of times --> even number
(??3(?!1).)* # followed only by strings that don't contain our quote char(s)
$ # until the end of the string
) # End of lookahead/sx',$subject))
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