> For the complete documentation index, see [llms.txt](https://xu-an.gitbook.io/sec/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://xu-an.gitbook.io/sec/ab/zzbds.md).

# 正则表达式

概念：\
就是正则表达式，英文是 Regular Expression，简称 RE。顾名思义，正则其实就是一种描述文本内容组成规律的表示方式

作用：

1. 校验数据的有效性，比如用户输入的手机号是不是符合规则
2. 可以从文本中提取想要的内容，比如从网页中抽取数据
3. 可以用来做文本内容替换


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