>>> import re

>>> re.findall("ab|c","sdfab|csdf")

['ab', 'c']

>>> re.findall("ab|cd","sdfab|cdsdf")

['ab', 'cd']

>>> re.findall ("abc+","abccccc")

['abccccc']

>>> re.findall ("abc*","abccccc")

['abccccc']

>>> re.findall("(abc)+","abcabcabcabc")               # 分组

['abc']

>>> re.findall ("(abc)*","abcabcabcabc")

['abc', '']

>>> re.findall ("abc+","abcabcabcabcabc")

['abc', 'abc', 'abc', 'abc', 'abc']

>>> re.search("(?P<name>\w+)","abcccc")

<re.Match object; span=(0, 6), match='abcccc'>

>>> re.search("(?P<name>\w+)","abcccc").group()

'abcccc'

>>> re.search("(?P<name>[a-z]+)\d+","john18musicxiaoming20movie").group("name")

'john'

>>> re.search("(?P<name>[a-z]+)(?P<age>\d+)","john18musicxiaoming20movie").group("age")

''

>>> 

>>> re.match("\d+","44safs45asdf321saf789").group()       # 只取一个对象，只能取开头的

''

>>> re.split(" ","hello world")                         # 按空格为分界线取

['hello', 'world']

>>> re.split("[ |]","hello world|aaa")

['hello', 'world', 'aaa']

>>> re.split("[ab]","safdbds")                         # 按 a  b 为分界线取

['s', 'fd', 'ds']

>>> re.sub("\d+","A","a1sd4fg45h")

'aAsdAfgAh'

>>> re.sub("\d","A","a1sd4fg45h")

'aAsdAfgAAh'

>>> re.sub("\d+","A","a1sd4fg45h",2)

'aAsdAfg45h'

>>> a = re.compile ("\d+")         # 定义规则

>>> a.findall("safsd12a45")           # 直接调用 （可以调用多次）

['', '']

>>> re.finditer ("\d+","asfa45saf56")         # 将数字放到迭代器内存里

<callable_iterator object at 0x00000220B1E50E80>

>>> b = re.finditer ("\d+","asfa45saf56")

>>> next(b)

<re.Match object; span=(4, 6), match=''>

>>> next(b)

<re.Match object; span=(9, 11), match=''>

>>> re.findall("www\.(baidu|123)\.com","www.baidu.com")

['baidu']

>>> re.findall("www\.(?:baidu|123)\.com","www.baidu.com")     # ‘ ？：’去掉优先级

['www.baidu.com']