Python的正则表达式的模块名字是‘re‘

>>> import re

>>> rawString = r‘This is a\nnormal string.‘

>>> rawString

‘This is a\nnormal string.‘

>>> string = ‘This is a\nnormal string.‘

>>> string

‘This is a

normal string.‘

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>>> match = re.match(r‘dog‘, ‘dog cat dog‘)

>>> match.group(0)

‘dog‘

.match()函数只能从字符串最开始进行匹配

>>> match = re.match(r‘cat‘, ‘dog cat dog‘)

>>> match

>>>

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.search()函数可以在字符串里从左到右自有匹配，不过只能匹配一次，查找到一个匹配项之后就停止

>>> match = re.search(r‘cat‘, ‘dog cat dog‘)

>>> match.group(0)

‘cat‘

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.findall()函数可以在字符串里，查找到所有匹配项，并放入一个列表中

>>> match = re.findall(r‘dog‘, ‘dog cat dog‘)

>>> match

[‘dog‘, ‘dog‘]

>>> match = re.findall(r‘cat‘, ‘dog cat dog‘)

>>> match

[‘cat‘]

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>>> match = re.search(r‘dog‘, ‘dog cat dog‘)

>>> match.start()

0

>>> match.end()

3

.start()与.end()两个函数，可用于告诉该匹配对象在字符串中的开始位置与结束为止

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>>> contaciInfo = ‘Doe, John: 555-1212‘

>>> match = re.search(r‘(?P<.last>\w+), (?P<first>\w+): (?P<phone>\S+)‘, contactInfo)

>>> match.group(‘last‘)

‘Doe‘

>>> match.group(‘first‘)

‘John‘

>>> match.group(‘phone‘)

‘555-1212‘

可以直接给分组命名，方便后续使用。不过.findall()函数不适用于命名

>>> re.findall(r‘(\w+), (\w+): (\S+)‘, contactInfo)

[(‘Doe‘, ‘John‘, ‘555-1212‘)]

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Python-正则表达式