python9

import re

#模式修正符
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I 匹配时忽略大小写
M 多行匹配
L 本地化识别匹配
U unicode
S 让.匹配包括换行
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string = “Python”
pat = “pyt”
result = re.search(pat,string)
print(result)
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None
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string = “Python”
pat = “pyt”
result = re.search(pat,string,re.I) #模式修正符 就是在加一个参数
print(result)
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<re.Match object; span=(0, 3), match=‘Pyt’>
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#贪婪模式与懒惰模式
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贪婪模式的核心就是尽可能多的匹配，而懒惰模式的核心点就是尽可能少的匹配
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#贪婪模式
string = “Pythony”
pat = “p.*y”
result = re.search(pat,string,re.I) #默认 就是 贪婪模式
print(result)
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<re.Match object; span=(0, 7), match=‘Pythony’>
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#懒惰模式
string = “Pythony”
pat = “p.*?y” #懒惰模式 就是 加一个 ？
result = re.search(pat,string,re.I)
print(result)
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<re.Match object; span=(0, 3), match=‘Poy’>
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#正则表达式函数
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re.match() 从头开始匹配
re.search() 可以从任意一个地方去匹配
re.sub() 自己了解
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string = “Pythony”
pat = “o.*?y” #懒惰模式 就是 加一个 ？
result = re.match(pat,string,re.I)
print(result)
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None
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string = “Pythony”
pat = “p.*?y” #懒惰模式 就是 加一个 ？
result = re.match(pat,string,re.I)
print(result)
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<re.Match object; span=(0, 2), match=‘Py’>
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#全局匹配函数：提取所有满足格式的字符
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格式：
re.compile(正则表达式).findall(数据)
re.compile(pat).findall(string)
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string = “Pythpaypiypmpony”
pat = “p.*?y”
result = re.compile(pat).findall(string)
print(result)
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[‘pay’, ‘piy’, ‘pmpony’]
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string = “Pythpaypiypmpony”
pat = “p.*?y”
result = re.search(pat,string,re.I)
print(result)
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<re.Match object; span=(0, 2), match=‘Py’>
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