正则表达式的常用方法

1. .：匹配除换行符外的任何单个字符

   • 示例：

     import re
     
     pattern = r".at"
     text = "cat hat sat bat"
     matches = re.findall(pattern, text)
     
     print(matches)  # 输出 ['cat', 'hat', 'sat', 'bat']
     

2. []：匹配方括号中列出的任何单个字符

   • 示例：

     import re
     
     pattern = r"[bh]at"
     text = "cat hat sat bat"
     matches = re.findall(pattern, text)
     
     print(matches)  # 输出 ['hat', 'bat']
     

3. \w：匹配任何字母数字字符或下划线字符

   • 示例：

     import re
     
     pattern = r"\w\w\w"
     text = "cat hat sat bat"
     matches = re.findall(pattern, text)
     
     print(matches)  # 输出 ['cat', 'hat', 'sat', 'bat']
     

4. \s：匹配任何空格字符，包括空格、制表符和换行符

   • 示例：

     import re
     
     pattern = r"\s\w\w\w"
     text = "cat hat\nsat\tbat"
     matches = re.findall(pattern, text)
     
     print(matches)  # 输出 [' hat', '\nsat', '\tbat']
     

5. \d：匹配任何十进制数字

   • 示例：

     import re
     
     pattern = r"\d+"
     text = "my age is 27"
     matches = re.findall(pattern, text)
     
     print(matches)  # 输出 ['27']
     

6. [^]：匹配除括号中列出的字符之外的任何单个字符

   • 示例：

     import re
     
     pattern = r"[^bh]at"
     text = "cat hat sat bat"
     matches = re.findall(pattern, text)
     
     print(matches)  # 输出 ['cat', 'sat']
     

     好的，以下是更多的正则表达式方法及其说明和示例：

7. \W：匹配任何非字母数字字符或下划线字符

   • 示例：

     import re
     
     pattern = r"\W\w+"
     text = "cat! hat sat_bat"
     matches = re.findall(pattern, text)
     
     print(matches)  # 输出 ['! hat', ' bat']
     

8. \S：匹配任何非空白字符

   • 示例：

     import re
     
     pattern = r"\S{3}"
     text = "cat hat\nsat\tbat"
     matches = re.findall(pattern, text)
     
     print(matches)  # 输出 ['cat', 'hat', 'sat', 'bat']
     

匹配多个字符

9. *：匹配前面的表达式零次或多次
   • 示例：

     import re
     
     pattern = r"ab*c"
     text = "ac abc abbc abbbc"
     matches = re.findall(pattern, text)
     
     print(matches)  # 输出 ['ac', 'abc', 'abbc', 'abbbc']
     

10. +：匹配前面的表达式一次或多次
    • 示例：

      import re
      
      pattern = r"a+b+c"
      text = "ac abc abbc abbbc"
      matches = re.findall(pattern, text)
      
      print(matches)  # 输出 ['abc', 'abbc', 'abbbc']
      

11. ?：匹配前面的表达式零次或一次
    • 示例：

      import re
      
      pattern = r"ab?c"
      text = "ac abc abbc abbbc"
      matches = re.findall(pattern, text)
      
      print(matches)  # 输出 ['ac', 'abc']
      

12. {n}：匹配前面的表达式恰好n次
    • 示例：

      import re
      
      pattern = r"ab{2}c"
      text = "ac abc abbc abbbc"
      matches = re.findall(pattern, text)
      
      print(matches)  # 输出 ['abbc']
      

13. {n,}：匹配前面的表达式至少n次
    • 示例：

      import re
      
      pattern = r"ab{2,}c"
      text = "ac abc abbc abbbc"
      matches = re.findall(pattern, text)
      
      print(matches)  # 输出 ['abbc', 'abbbc']
      

14. {n,m}：匹配前面的表达式至少n次且不超过m次
    • 示例：

      import re
      
      pattern = r"ab{1,2}c"
      text = "ac abc abbc abbbc"
      matches = re.findall(pattern, text)
      
      print(matches)  # 输出 ['abc', 'abbc']