一、从文本中提取信息
从复杂文本中提取特定信息，例如提取电话号码、日期等：
import re
text = "Contact us at support@example.com or call us at (555) 123-4567"
email_pattern = r'[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+'
phone_pattern = r'\(\d{3}\) \d{3}-\d{4}'
emails = re.findall(email_pattern, text)
phones = re.findall(phone_pattern, text)
print(emails) # 输出 ['support@example.com']
print(phones) # 输出 ['(555) 123-4567']
二、去除字符串中的多余空白
清理用户输入或格式化文本：
import re
text = " This is a sentence with irregular spacing. "
cleaned_text = re.sub(r'\s+', ' ', text).strip()
print(cleaned_text) # 输出 This is a sentence with irregular spacing.
三、提取HTML中的内容
从HTML文件或字符串中提取特定内容，例如提取所有链接、标题等：
import re
html = """
<html>
<head><title>Example Title</title></head>
<body>
<h1>Example Header</h1>
<p>This is an example paragraph.</p>
<a href="http://example.com">Link</a>
</body>
</html>
"""
# 提取所有链接
links = re.findall(r'href="(http[s]?://.*?)"', html)
print(links) # 输出 ['http://example.com']
# 提取标题
title = re.search(r'<title>(.*?)</title>', html)
if title:
print(title.group(1)) # 输出 Example Title
四、验证密码强度
验证用户输入的密码是否符合强度要求，例如包含大小写字母、数字和特殊字符：
import re
def is_strong_password(password):
pattern = r'^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$'
return re.match(pattern, password) is not None
password = "StrongPass1!"
print(is_strong_password(password)) # 输出 True