Python正则表达式中?!的用法详解

import re
pattern = r'^(?!admin)\w+$'
print(re.match(pattern, "user123"))  # 匹配成功
print(re.match(pattern, "adminuser"))  # 匹配失败

pattern = r'(?<!\$)\d+'
print(re.search(pattern, "123"))  # 匹配123
print(re.search(pattern, "$456"))  # 匹配失败

import re

def validate_password(username, password):
    # 排除用户名
    if re.search(rf'(?i){username}', password):
        return "密码不能包含用户名"
    # 复杂度校验
    rules = [
        (r'.{8,}', "至少8位"),
        (r'[a-z]', "包含小写字母"),
        (r'[a-z]', "包含大写字母"),
        (r'\d', "包含数字"),
        (r'[!@#$%^&*]', "包含特殊字符")
    ]
    failed_rules = [msg for pat, msg in rules if not re.search(pat, password)]
    return failed_rules or "密码有效"

log = """info: operation started
error: disk full
debug: debugging complete"""
filtered = re.findall(r'^(?:(?!error).)*$', log, re.ignorecase | re.multiline)
# 输出：['info: operation started\n', 'debug: debugging complete']

urls = ['/api/user', '/test/v1', '/report/test']
valid_urls = [u for u in urls if re.search(r'^(?!.*test).+$', u)]
# 输出：['/api/user']

routes = ['/home', '/admin/dashboard', '/user/profile']
public_routes = [r for r in routes if not re.search(r'/admin', r)]
# 输出：['/home', '/user/profile']

^(?!.*admin).+$  # 在长文本中匹配时，引擎需遍历所有可能路径

pattern = r'^(?=.*[a-z])(?!.*abc).+$'
re.match(pattern, "xyz123")  # 匹配成功
re.match(pattern, "abcdef")  # 匹配失败

amounts = ["100.00", "税后200", "300元"]
valid = [a for a in amounts if re.match(r'^\d+\.?\d{0,2}$(?<!税)', a)]
# 输出：['100.00', '300元']