import re
re.findall() 查询到所有符合的
re.search
re.match
re.compile
flags 修改正则的匹配规则
特殊符号
"." 除换行符外的任意字符
"^" 匹配开头
"$" 匹配结尾
"*" 重复前一个字符0或尽可能多次
"+" 重复前一个字符1或尽可能多次
"?" 重复前一个字符0或1次
*?,+?,?? 非贪婪模式
{m,n} 匹配前一个字符m~n次，贪婪模式
{m,n}? {m,n}的非贪婪模式，等同于{m}
"\\" 转义\
[a-z] 匹配a-z
[^a-z] 匹配非a-z
A|B 匹配A或B
(...) 分组，可以在后面取回
(?aiLmsux) Set the A, I, L, M, S, U, or X flag for the RE (see below).
(?:...) Non-grouping version of regular parentheses.
(?P<name>...) 设置命名分组
(?P=name) Matches the text matched earlier by the group named name.
(?#...) A comment; ignored.
(?=...) Matches if ... matches next, but doesn't consume the string.
(?!...) Matches if ... doesn't match next.
(?<=...) Matches if preceded by ... (must be fixed length).
(?<!...) Matches if not preceded by ... (must be fixed length).
(?(id/name)yes|no) Matches yes pattern if the group with id/name matched,
the (optional) no pattern otherwise.
\number 匹配分组内容.
\A 只匹配开头，类似^
\Z 只匹配结尾，类似$
\b Matches the empty string, but only at the start or end of a word.
\B Matches the empty string, but not at the start or end of a word.
\d 匹配数字，等价于 [0-9]
\D 匹配非数字，等价于 [^\d].
\s 匹配所有空格，等价于 [ \t\n\r\f\v]
\S 匹配所有非空格，等价于[^\s].
\w 匹配字符数字下划线，等价于 [a-zA-Z0-9_]
\W Matches the complement of \w.
\\ 匹配\
group(0) 打所有分组信息
group(1) 打一个分组信息
group('name') 打印命名分组名称为name的内容
