1.1正则表达式概述
正则表达式,又称正规表示式、正规表示法、正规表达式、规则表达式、常规表示法(英语:RegularExpression,在代码中常简写为regex、regexp或RE),是计算机科学的一个概念。正则表达式使用单个字符串来描述、匹配一系列匹配某个句法规则的字符串。
![](https://img.haomeiwen.com/i8777041/fe8fb2d4f8bdf33c.png)
1、单字符匹配
![](https://img.haomeiwen.com/i8777041/63499cc0c0e45a06.png)
![](https://img.haomeiwen.com/i8777041/a98ff236dbc0af5d.png)
![](https://img.haomeiwen.com/i8777041/75cac16e2b603e5f.png)
![](https://img.haomeiwen.com/i8777041/87e769164858b4c3.png)
2、原始字符串
![](https://img.haomeiwen.com/i8777041/17397ebd8d5ee468.png)
3、表示数量
![](https://img.haomeiwen.com/i8777041/519a38b14a9f4008.png)
![](https://img.haomeiwen.com/i8777041/4ac631727d8a75cd.png)
4、表示边界
![](https://img.haomeiwen.com/i8777041/f6580047550700fe.png)
![](https://img.haomeiwen.com/i8777041/edfdda4aa7148ca9.png)
5、表示分组
![](https://img.haomeiwen.com/i8777041/4e90ace4461a0961.png)
![](https://img.haomeiwen.com/i8777041/2e609e8c71224d33.png)
6、正则表达式的函数
![](https://img.haomeiwen.com/i8777041/a18364055d650016.png)
1、match()
![](https://img.haomeiwen.com/i8777041/66085edf3cc48fc2.png)
2、search()
![](https://img.haomeiwen.com/i8777041/235803dd60a251c2.png)
3、findall()
![](https://img.haomeiwen.com/i8777041/99f3b251e846184d.png)
4、finditer()
![](https://img.haomeiwen.com/i8777041/8f9226ac283c649c.png)
5、sub()
![](https://img.haomeiwen.com/i8777041/386fbd74b1eff6e1.png)
![](https://img.haomeiwen.com/i8777041/c02a111fdebcabf0.png)
![](https://img.haomeiwen.com/i8777041/f9e8ff0693c09120.png)
7、split()
![](https://img.haomeiwen.com/i8777041/1e00c08b3ef6b6f1.png)
8、贪婪模式和非贪婪模式
![](https://img.haomeiwen.com/i8777041/e90a8d3364f673b8.png)
练习:
![](https://img.haomeiwen.com/i8777041/eb2997721535c755.png)
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