Python 正则表达式笔记（2）单字符匹配

古城微笑少年丶 2022-05-25 00:38 171阅读 0赞

正则表达式的单字符匹配

<table style="border-spacing:0px;font-size:16px;margin-top:0px;margin-bottom:.85em;width:770px;color:rgb(51,51,51);font-family:'Helvetica Neue', Helvetica, Arial, sans-serif;letter-spacing:.2px;"> 
 <thead> 
  <tr style="border-top-color:rgb(204,204,204);"> 
   <th style="padding:6px 13px;text-align:center;">字符</th> 
   <th style="padding:6px 13px;">功能</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr style="border-top-color:rgb(204,204,204);"> 
   <td style="padding:6px 13px;text-align:center;">.</td> 
   <td style="padding:6px 13px;">匹配任意1个字符（除了\n）</td> 
  </tr> 
  <tr style="background-color:rgb(248,248,248);border-top-color:rgb(204,204,204);"> 
   <td style="padding:6px 13px;text-align:center;">[ ]</td> 
   <td style="padding:6px 13px;">匹配[ ]中列举的字符</td> 
  </tr> 
  <tr style="border-top-color:rgb(204,204,204);"> 
   <td style="padding:6px 13px;text-align:center;">\d</td> 
   <td style="padding:6px 13px;">匹配<span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">任意<span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">1个</span></span>数字，即0-9</td> 
  </tr> 
  <tr style="background-color:rgb(248,248,248);border-top-color:rgb(204,204,204);"> 
   <td style="padding:6px 13px;text-align:center;">\D</td> 
   <td style="padding:6px 13px;">匹配<span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">任意</span><span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">1个</span>非数字，即不是数字</td> 
  </tr> 
  <tr style="border-top-color:rgb(204,204,204);"> 
   <td style="padding:6px 13px;text-align:center;">\s</td> 
   <td style="padding:6px 13px;">匹配<span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">任意</span><span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">1个</span>空白，即 空格，tab键</td> 
  </tr> 
  <tr style="background-color:rgb(248,248,248);border-top-color:rgb(204,204,204);"> 
   <td style="padding:6px 13px;text-align:center;">\S</td> 
   <td style="padding:6px 13px;">匹配<span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">任意</span><span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">1个</span>非空白</td> 
  </tr> 
  <tr style="border-top-color:rgb(204,204,204);"> 
   <td style="padding:6px 13px;text-align:center;">\w</td> 
   <td style="padding:6px 13px;">匹配<span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">任意</span><span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">1个</span>单词字符，即a-z、A-Z、0-9、_</td> 
  </tr> 
  <tr style="background-color:rgb(248,248,248);border-top-color:rgb(204,204,204);"> 
   <td style="padding:6px 13px;text-align:center;">\W</td> 
   <td style="padding:6px 13px;">匹配<span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">任意</span><span style="font-family:Arial, Verdana, sans-serif;letter-spacing:.2px;text-align:left;background-color:rgb(255,255,255);">1个</span>非单词字符</td> 
  </tr> 
 </tbody> 
</table>

### 示例1： . ###

#coding=utf-8
    
        import re
    
        ret = re.match(".","a")
        ret.group()
    
        ret = re.match(".","b")
        ret.group()
    
        ret = re.match(".","M")
        ret.group()

运行结果：

![20180505104947126][]

### 示例2：\[ \] ###

#coding=utf-8
    
        import re
    
        # 如果hello的首字符小写，那么正则表达式需要小写的h
        ret = re.match("h","hello Python")
        ret.group()
    
    
        # 如果hello的首字符大写，那么正则表达式需要大写的H
        ret = re.match("H","Hello Python")
        ret.group()
    
        # 大小写h都可以的情况
        ret = re.match("[hH]","hello Python")
        ret.group()
        ret = re.match("[hH]","Hello Python")
        ret.group()
    
        # 匹配0到9第一种写法
        ret = re.match("[0123456789]","7Hello Python")
        ret.group()
    
        # 匹配0到9第二种写法
        ret = re.match("[0-9]","7Hello Python")
        ret.group()

运行结果：

![20180505105014311][]

### 示例3：\\d ###

#coding=utf-8
    
        import re
    
        # 普通的匹配方式
        ret = re.match("嫦娥1号","嫦娥1号发射成功")
        print ret.group()
    
        ret = re.match("嫦娥2号","嫦娥2号发射成功")
        print ret.group()
    
        ret = re.match("嫦娥3号","嫦娥3号发射成功")
        print ret.group()
    
        # 使用\d进行匹配
        ret = re.match("嫦娥\d号","嫦娥1号发射成功")
        print ret.group()
    
        ret = re.match("嫦娥\d号","嫦娥2号发射成功")
        print ret.group()
    
        ret = re.match("嫦娥\d号","嫦娥3号发射成功")
        print ret.group()

运行结果：

![20180505105030950][]

### 说明 ###

*  其他的匹配符参见后面章节的讲解

[20180505104947126]: /images/20220525/87af501980fe4cb0b8d45814d5f11da5.png
[20180505105014311]: /images/20220525/e978e5f56dde4803ac833ec6df41a3c1.png
[20180505105030950]: /images/20220525/6b92d31ed0614640afa862d996715293.png