正则表达式中反斜杠后的数字是什么意思? [英] What's the meaning of a number after a backslash in a regular expression?

问题描述

(a|b)\1

\1 在这个表达式中是什么意思?

What does \1 mean in this expression?

推荐答案

\1 - 表示匹配表达式中的第一个捕获组.\n 将是第 n 个捕获组.(请注意 \0 将是完整匹配).在许多引擎中，n 的上限是 9，但有些引擎也支持高达 99.

\1 - it means the first capturing group in the matched expression. \n would be the nth capturing group. (Note that \0 would be whole match). In many engines, the upperlimit for n is 9, but some support up to 99 as well.

当在正则表达式中使用时，如(a|b)\1，表示在a或b之后，下一个字符应该是第一个捕获的组，即a或b，所以这里的正则表达式将匹配 aa 或 bb.

When used in regex like (a|b)\1, it means that after a or b, the next character should be the first captured group, which is a or b so the regex here would match aa or bb.

这篇关于正则表达式中反斜杠后的数字是什么意思?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！