Core module
import re
General Syntax
- .
- []
a set of chars, common cases as follows:
(1)chars list
(2)chars range
(3)special chars lose special meanings, like “[(+)]” will match “(” , “+” and “)”
(4)not within chars range, like “[^5]” match any chars except “5” - ()
?
zero or one repetion of 前面一个RE或字符。
Like “ab?” it indicates either “a” or “ab”+
one or more repetions of 前面一个RE或字符。
Like“ab+”, it indcates “a” can be followed by non-zero number of “b”.*
zero or more repetions of 前面一个RE或字符。
Like “ab*” , it indicates “a” can be followed by any number of “b”.*? , +? , ??
add ? after * , + , ? will execute in non-greedy or minimal fashion
Like “<.*?>” only match “<\a>” in “<\a>b<\c>”.(Note: “\” is an escaping character)\s
match any whitesapce chars as “[ \t\r\n\f\v]” if UNICODE flag not specified.
Key Methods
- match : used for str match
- search : used for str search
- sub : used for str search and replace
这部分的关键点在于对于具体的应用需求，构建regex pattern.
Application Case and experience
(1)specific tag search in xml and update its value
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在匹配时,单个\s字符就可以匹配所有连续空格；
Note:多行匹配；方法中编译标识的掌握与灵活运用，如flags=re.S使得 “.”匹配任意字符包括新行(\n).
(2)similar str style match verification
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