正则表达式/“正则表达式"中的正则是什么?意思是? [英] what does regular in regex/"regular expression" mean?

问题描述

正则表达式"中的正则"是什么意思?

What does the "regular" in the phrase "regular expression" mean?

我听说正则表达式一次是常规的，但是没有更多了

I have heard that regexes were regular at one time, but no more

推荐答案

正则表达式中的正则来自与

The regular in regular expression comes from that it matches a regular language.

形式语言理论中使用的正则表达式的概念与哪些引擎完全不同像 PCRE 一样调用正则表达式. PCRE和其他类似的引擎具有类似前瞻，

The concept of regular expressions used in formal language theory is quite different from what engines like PCRE call regular expressions. PCRE and other similar engines have features like lookahead, conditionals and recursion, which make them able to match non-regular languages.

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