python 正则之字母匹配

\A:匹配字符串的开始

 

\b：匹配一个单词边界

 

取出a边界单词的个数

>>> len(re.findall(r"\ba"," ab abc add"))

3

\B:匹配非单词边界

 

\d:匹配任意一个数字范围【0-9】

• >>> re.match(r"\d+","123abc")
• <_sre.SRE_Match object at 0x000000000202A510>

\D:匹配任意一个非数字字符== [^\d]

• >>> re.match(r"\D+","ABC123").group()
• 'ABC'

\s：匹配空白字符 练习

>>> print re.match(r"\s"," 13d")

<_sre.SRE_Match object at 0x0000000001F1A510>

\S:匹配非空白字符

>>> print re.match(r"\S","13d")

<_sre.SRE_Match object at 0x0000000001F1A510>

\w:匹配单个字符（数字或字母）

>>> print re.match(r"\w","13d")

<_sre.SRE_Match object at 0x0000000001F1A510>

\w+:匹配多个字符（数字或字母）

>>> print re.match(r"\w+","13d")

<_sre.SRE_Match object at 0x0000000001F1A510>

>>> re.match(r"\w+","13d")

<_sre.SRE_Match object at 0x0000000001F1A510>

>>> re.match(r"\w+","13d").group()

'13d'

 

>>> re.match(r"\D+","13d").group()

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

AttributeError: 'NoneType' object has no attribute 'group'

\W:非单词字符，等价于[^\w]