正则表达式匹配直到某个字符的第一个实例 [英] Regex match until first instance of certain character

问题描述

我试图匹配一个 url 直到一个特殊字符，但是当我需要它在第一个实例之后停止时，我使用的正则表达式匹配最后一个实例.我做错了什么?！

I am trying to match a url up until a special character however the regex I am using is match the last instance when I need it to stop after the first instance. What am I doing wrong?!

.+?(?=\")

匹配所有内容直到第一个 "

To match everything until first "

但是我的结果如下:

推荐答案

您将 " 添加到模式的使用部分，将其删除.

You added the " into the consuming part of the pattern, remove it.

^.+?(?=\")

或者，如果您需要匹配任何字符，包括换行符，请使用任一

Or, if you need to match any chars including line breaks, use either

(?s)^.+?(?=\")
^[\w\W]+?(?=\")

请参阅演示.这里，^ 匹配字符串的开头，.+? 匹配任何 1+ 个字符，尽可能少，直到第一个 " 不包括它来自匹配，因为"是前瞻的一部分(零宽度断言).

See demo. Here, ^ matches start of string, .+? matches any 1+ chars, as few as possible, up to the first " excluding it from the match because the "` is a part of the lookahead (a zero-width assertion).

在另外两个正则表达式中，(?s) 使点匹配跨行，而 [\w\W] 是一种变通构造，可以匹配任何如果不支持 (s)(或其 /s 形式)，则为 char.

In the two other regexps, (?s) makes the dot match across lines, and [\w\W] is a work-around construct that matches any char if the (s) (or its /s form) is not supported.

最好使用否定字符类:

^[^"]+

查看另一个演示.这里，^[^"]+ 从头开始​​匹配 1+ 个除 " 以外的字符(参见 [^"]+)一个字符串 (^).

See another demo. Here, ^[^"]+ matches 1+ chars other than " (see [^"]+) from the start of a string (^).

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