Brief analysis of common regular expression symbols in Python

The understanding of the expression in Python is mainly the understanding of the symbol, which is a simple analysis of the regular expression symbols commonly used in Python. The main symbols are:

.
Matches a character by default, does not contain newline characters, and matches line breaks if set Dotall

^
Match beginning

$
Match end of Line

*
Match 0 or more repetitions

+
Match one or more duplicates

？
Match one or 0 duplicates

*?,+?,??
Match by non-greedy pattern

{m},{m,n},{m,n}?
Match M repeats, M to n repeats, M to n repeats in non-greedy mode

\
Escape

[]
[Abc],[a-z][^a-z]
|
or match ' a|b '
(...)
Matching groups

(? ilmsux) (?:...) (? P
 
  
   
  ...) >>> Re.match (' (? P
  
   
    
   ABC) {2} ', ' Abcabc '). Groupdict () {' name ': ' ABC '} (? P=name) >>> Re.match (R ' (? P
   
    
     
    ABC)----(? P=name) ', ' ABC----ABC '). Group () ' ABC----ABC ' (? # ...) #后面的内容为注释 (? = ...
   
    
  
    )
 
  

The content following the matched string needs to be matched

>>> Re.match (R ' Phone (=\d{3}) ', ' phone123 '). Group () ' Phone ' # (?! ...)

Matches the character after the content does not match

>>> Re.match (R ' Phone (?! \d{3}) ', ' phoneabc123 '). Group () ' Phone ' (? <= ...)

Matching strings need to be matched in front of

(?

(? (id/name) Yes-pattern|no-pattern)
\number
\a matches the beginning of a string
\b Match word boundaries

\b
\b's anti-righteousness

\d = [0-9]
\d said [^0-9]
\s said [\t\r\n\f\v]
\s as non-whitespace characters
\w equivalent to [a-za-z0-9]
\w \w's anti-righteousness

\z the end of the matching string

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