Python basic five--regular expression

Regular expressions

First, query function

ImportRes='Besttest is good are'Print(Re.match (R' be', s). Group ())#string pre-plus R for the original string#The match method receives 3 parameters, the first one is the regular expression, the second is the string to look for, the third is not required, and the match is used to control the regular pattern.#is to match the string from the first word if it matches to return an object, otherwise, returns nonePrint(Re.search (R' is', s). Group ())#search is from the entire content, found on the return to the first, not found to return nonePrint(Re.findall (R' is', s))#Find all the stringsPrint(Re.sub (R' is','is very', s))#Replace stringPrint(Re.split (' is', s))#Split String

Second, the number of words

Import RE

1 Print(Re.findall (R'be*e','b be beebest is very OK'))# ^Match * One of the preceding characters appears 0 or more times2 Print(Re.findall (R'st+','Besttest is the best s'))#+ Match previous character 1 or more times, just + one character in front3 Print(Re.findall (R'St?','Besttest is the best s'))#? Match the previous character 0 or 1 times, just? One of the preceding characters4 Print(Re.findall (R'T{2}er','besttest is best letter'))#{n} matches the previous character N times 5 Print(Re.findall (R't{1,3}','Besttest is the best letterv ttt'))#{n,m} matches the previous character N to M times

C. General characters

 Import re

1 Print(Re.findall (R'B.','besttest is best letter'))#. The default match is any character except \ n2 Print(Re.findall (R'\?','BES??? TTest is best letter'))#\ Translator, front of * +? These characters have special meanings, and if you need to find them, you have to translate them.3 Print(Re.findall (R'Best|is','besttest is best'))#| match | left or | right character4 Print(Re.findall (R'E[ras]','besttest is best letter'))#[] Set of character sets, the collection of Capricorn characters, which matches any one of the set.5 Print(Re.findall (R'E[^ras]','besttest is best letter'))#If you use ^ in [], it means that you don't include these strings.

　　

Iv. Boundary Matching

 Import re

1 Print(Re.findall (R'^http://','http://www.baidu.com Besttest is good\nbest'))#^ matches start with what character, and multiple lines match the beginning of each line2 Print(Re.findall (R'^b','Besttest is good\nbest', Re. M))#Re. M is multi-line mode3 Print(Re.findall (R'jpge$|png|npg$','Touxiang.png'))#$ matches what character ends and matches the end of each line in multiple lines4 Print(Re.findall (R'\ahttp://','http://www.baidu.com\nhttp://www.souhu.com', Re. M))#\a only begins with what character, and ^ different is that it cannot be used in multiline mode5 Print(Re.findall (R'\.jpge\z|\.png\z|\.npg\z','TOUXIANG.PNG\NYI.NPG', Re. M))#\z Only the end of what character, and the difference is that it cannot be used in multiline mode

V. Predefined character sets

 Import re

1 Print(Re.findall (R'\d','S135434657EHFU243FDSF'))#\d Match Number 0-9 # [A-z] case letter [0-9] number2 Print(Re.findall (R'\d+','S135434657EHFU243FDSF'))3 Print(Re.findall (R'\d','S135434657EHFU243FDSF'))#\d matches non-numeric4 Print(Re.findall (R'\w','s13543465^*[email protected] Hello F'))#\w matches all letters, numbers and Chinese5 Print(Re.findall (R'\w','S13543465^*[email protected]'))#\w matches are not letters and numbers6 Print(Re.findall ('\s','We j\tr \NOE\RHGORHG'))#\s matching whitespace characters: \ t, \ n, \ r, Space7 Print(Re.findall ('\s','We j\tr \NOE\RHGORHG'))#\s matches non-whitespace characters

Six, group matching

#Group Matching#such as matching IP addressPrint(Re.findall (R'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}','192.168.160.3'))#GroupingPrint(Re.search (R'\d{1,3} (\.\d{1,3}) {3}','192.168.160.3'). Group ())Print(Re.findall (R'\d{1,3} (\.\d{1,3}) {3}','192.168.160.3'))#FindAll There are groups, the default result is only the contents of the group, that is, the contents of the parentheses.Print(Re.findall (R'\d{1,3} (?: \. \d{1,3}) {3}','192.168.160.3'))

Python basic five--regular expression