为什么此正则表达式断言不匹配? [英] Why this regex assertion doesn't match?

问题描述

我正在尝试在html标签之间准备内容，我正在尝试这种简单的断言模式，但我不明白为什么它与该字符串不匹配.

I'm trying to just preg content between html tags, I'm trying this simple assertion pattern and I don't understand why it doesn't match this string.

<a href=http://url.com title="link">this is a ling</a>

(?<=<a.*>)([ \w]*)(?=<.*\/a>)

Debuggex演示

推荐答案

debuggex(PCRE，Javascript和Python)上的隐藏内容不能具有可变宽度，这意味着您可以使用固定宽度(3个字符)的(?<=<a>)但长度不能变化的东西(?<=<a.*>)(可以包含3个字符，也可以是4个或5个字符，等等).

Lookbehinds on debuggex (PCRE, Javascript and Python) cannot be of variable width, meaning that you can use (?<=<a>) which has a fixed width (3 characters) but not something that can vary in length (?<=<a.*>) (can have 3 characters, or 4, or 5, etc).

正则表达式完全无效，但是debuggex告诉您没有匹配项.

The regex simply is not valid but debuggex tells you that there is no match.

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