How do you use the regex module in Python?

In Python, the regular expression module is called the re module and can be used by following these steps:

1. Import the re module.

import re

1. Create a regular expression pattern.

pattern = re.compile(r'正则表达式模式')

In this case, r represents the original string, which can avoid the issue of escape characters.

1. Match or replace in the text:

result = pattern.match(文本)  # 从文本开头开始匹配
result = pattern.search(文本)  # 在文本中搜索匹配项
result = pattern.findall(文本)  # 返回所有匹配项的列表
result = pattern.finditer(文本)  # 返回所有匹配项的迭代器
result = pattern.sub(替换字符串, 文本)  # 替换匹配项为指定字符串

Among them, the match() function only matches the beginning part, the search() function searches for matching items throughout the entire text, the findall() function returns a list of all matching items, the finditer() function returns an iterator for all matching items, and the sub() function is used to replace matching items with a specified string.

1. Deal with the matching results.

if result:
    print('匹配成功')
    print(result.group())  # 返回匹配到的字符串
else:
    print('匹配失败')

You can use the group() function to retrieve the matched string.

This is a simple example of using regular expressions. For specific regular expression syntax, you can refer to the Python official documentation or other regex tutorials.