python正则表达式3-模式匹配

re.S，使 '.'  匹配换行在内的所有字符

>>> pattern=r'ghostwu.com'
>>> import re
>>> re.findall( pattern, 'ghostwuacom' )
['ghostwuacom']
>>> re.findall( pattern, 'ghostwubcom' ) 
['ghostwubcom']
>>> re.findall( pattern, 'ghostwu.com' ) 
['ghostwu.com']
>>> re.findall( pattern, 'ghostwu
com' ) 
[]
>>> re.findall( pattern, 'ghostwu
com', re.S )
['ghostwu
com']
>>> 

re.M，多行匹配，主要影响( ^和$ )

>>> str="""
... hi,ghostwu,how are you
... ghostwu: my name is ghostwu,how are you
... ghostwu: nice to meet you
... hello ghostwu
... """
>>> pattern = r"^ghostwu"
>>> re.findall( pattern, str )
[]
>>> re.findall( pattern, str, re.M )
['ghostwu', 'ghostwu']
>>> 

当正则有多行的时候，可以开启verbose模式re.X

>>> pattern=r"""
... d{3,4}
... -?
... d{8}
... """
>>> str="020-88888888"
>>> re.findall( pattern, str )
[]
>>> re.findall( pattern, str, re.X )
['020-88888888']
>>> 

():分组与|  的使用，  假如我们要匹配一个.com,.cn,.net结尾的email

>>> pattern=r"w+@w+(.com|.cn|.net)"
>>> email="abc@qq.com">>> re.match( pattern, email )
<_sre.SRE_Match object at 0x7f2b74481828>
>>> re.match( pattern, 'abc@qq.cn' )
<_sre.SRE_Match object at 0x7f2b744818a0>
>>> re.match( pattern, 'abc@qq.net' )
<_sre.SRE_Match object at 0x7f2b74481828>
>>> re.match( pattern, 'abc@qq.io' )
>>> 

匹配超链接

>>> html="""
... <a href="http://www.baidu.com">百度</a>
... <a href="index.html">首页</a>
... <p>这是一段说明</p>
... <a href="http://www.taobao.com">淘宝</a>
... """
>>> re=r"href="(.+?)""
>>> pattern=r"href="(.+?)""
>>> re
'href=\"(.+?)\"'
>>> import re
>>> re.findall( pattern, html )
['http://www.baidu.com', 'index.html', 'http://www.taobao.com']
>>>