python正则表达式（三）

表示边界

示例1：$

需求：匹配163.com的邮箱地址

#coding=utf-8

import re

# 正确的地址
ret = re.match("[w]{4,20}@163.com", "xiaoWang@163.com")
ret.group()

# 不正确的地址
ret = re.match("[w]{4,20}@163.com", "xiaoWang@163.comheihei")
ret.group()

# 通过$来确定末尾
ret = re.match("[w]{4,20}@163.com$", "xiaoWang@163.comheihei")
ret.group()

示例2: 

>>> re.match(r".*ver", "ho ver abc").group()
'ho ver'

>>> re.match(r".*ver", "ho verabc").group()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'group'

>>> re.match(r".*ver", "hover abc").group()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'group'

示例3：B

>>> re.match(r".*BverB", "hoverabc").group()
'hover'

>>> re.match(r".*BverB", "ho verabc").group()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'group'

>>> re.match(r".*BverB", "hover abc").group()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'group'

>>> re.match(r".*BverB", "ho ver abc").group()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'group'

匹配分组

示例1：|

需求：匹配出0-100之间的数字

#coding=utf-8

import re

ret = re.match("[1-9]?d","8")
ret.group()

ret = re.match("[1-9]?d","78")
ret.group()

# 不正确的情况
ret = re.match("[1-9]?d","08")
ret.group()

# 修正之后的
ret = re.match("[1-9]?d$","08")
ret.group()

# 添加|
ret = re.match("[1-9]?d$|100","8")
ret.group()

ret = re.match("[1-9]?d$|100","78")
ret.group()

ret = re.match("[1-9]?d$|100","08")
ret.group()

ret = re.match("[1-9]?d$|100","100")
ret.group()

示例2：( )

需求：匹配出163、126、qq邮箱之间的数字

#coding=utf-8

import re

ret = re.match("w{4,20}@163.com", "test@163.com")
ret.group()

ret = re.match("w{4,20}@(163|126|qq).com", "test@126.com")
ret.group()

ret = re.match("w{4,20}@(163|126|qq).com", "test@qq.com")
ret.group()

ret = re.match("w{4,20}@(163|126|qq).com", "test@gmail.com")
ret.group()