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""" 1、什么是正则 正则就是用一系列具有特殊含义的字符组成一套规则，该规则用来描述具有某一特征的字符串， 正则就是用来去一个大的字符串中匹配出符合规则的子字符串 2、为什么要用正则 1、用户注册 2、爬虫程序 3、如何用正则 """ import re # print(re.findall('\w','hello 123_ */-=')) # print(re.findall('\W','hello 123_ */-=')) # print(re.findall('\s','hell\no 12\t3_ */-=')) # print(re.findall('\S','hell\no 12\t3_ */-=')) # print(re.findall('\d','hell\no 12\t3_ */-=')) # print(re.findall('\D','hell\no 12\t3_ */-=')) # print(re.findall('\n','hell\no 12\t3_ */-=')) # print(re.findall('\t','hell\no 12\t3_ */-=')) # print(re.findall('l','hell\no 12\t3_ */-=')) # print(re.findall('egon','my name is egon,egon is beautiful')) # egon # print(re.findall('^egon','egon my name is egon,egon is beautiful')) # print(re.findall('egon$','egon my name is egon,egon is beautifulegon1')) # egon # 重复匹配 # .:匹配换行符以外的任意一个字符 # print(re.findall('a.c','abc a1c aac asd aaaaac a*c a+c abasd')) #['abc','a1c','aac','aac','a*c','a+c'] # a.c # print(re.findall('a.c','abc a1c aac a\nc asd aaaaac a*c a+c abasd',re.DOTALL)) # []:匹配一个字符,该字符属于中括号内指定的字符 # print(re.findall('a..c','abc a1 c aac asd aaaaac a *c a+c abasd =')) # print(re.findall('a.c','abc a1 c aac aAc aBc asd aaaaac a-c a/c a *c a+c abasd = a1c a2c')) # print(re.findall('a[a-z]c','abc a1 c aac aAc aBc asd aaaaac a-c a/c a *c a+c abasd = a1c a2c')) # print(re.findall('a[A-Z]c','abc a1 c aac aAc aBc asd aaaaac a-c a/c a *c a+c abasd = a1c a2c')) # print(re.findall('a[-+*/]c','abc a1 c aac aAc aBc asd aaaaac a-c a/c a *c a+c abasd = a1c a2c')) # print(re.findall('a[a-z][a-z]c','abc a1 c aac aAc aBc asd aaaaac a-c a/c a *c a+c abasd = a1c a2c')) # print(re.findall('a[^a-z]c','abc a1 c aac aAc aBc asd aaaaac a-c a/c a *c a+c abasd = a1c a2c')) # *: 必须与其他字符连用，代表左侧的字符出现0次或者无穷次 # print(re.findall('ab*','a ab abbb abbbb a1bbbb a-123')) # ab* #['a','ab','abbb','abbbb','a','a'] # print(re.findall('ab{0,}','a ab abbb abbbb a1bbbb a-123')) # ?： 必须与其他字符连用,代表左侧的字符出现0次或者1次 # print(re.findall('ab?','a ab abbb abbbb a1bbbb a-123')) # ab? #['a','ab','ab','ab','a','a'] # print(re.findall('ab{0,1}','a ab abbb abbbb a1bbbb a-123')) # +： 必须与其他字符连用,代表左侧的字符出现1次或者无穷次 # print(re.findall('ab+','a ab abbb abbbb a1bbbb a-123')) # ab+ # ['ab','abbb','abbbb'] # print(re.findall('ab{1,}','a ab abbb abbbb a1bbbb a-123')) # {n,m}： 必须与其他字符连用 # print(re.findall('ab{1,3}','a ab abbb abbbb a1bbbb a-123')) # ab{1,3} # ['ab','abbb','abbb'] # .*：贪婪匹配 # print(re.findall('a.*c','ab123adfc1134124123adasfc123123')) # .*?:非贪婪匹配 # print(re.findall('a.*?c','ab123adfc1134124123adasfc123123')) # a.*?c #():分组 # print(re.findall('expression="(.*?)"','expression="1+2+3/4*5" egon="beautiful"')) # expression=".*?" # print(re.findall('href="(.*?)"','<p>段落</p><a href="https://www.sb.com">点我啊</a><h1>标题</h1><a href="https://www.sb.com">点我啊</a>')) #|： # print(re.findall('a|b','ab123abasdfaf')) # a|b # print(re.findall('compan(?:ies|y)','Too many companies have gone bankrupt, and the next one is my company')) #companies company # print(re.findall(r'a\\c','a\c a1c aAc aac')) # print(re.findall('a\\\\c','a\c a1c aAc aac')) # print(re.findall('ale(x)','alex is SB,alex is bigSB')) # print(re.search('alex','alex is SB,alex is bigSB')) # print(re.search('ale(x)','alex is SB,alex is bigSB').group()) # print(re.search('abcdefg','alex is SB,alex is bigSB')) # print(re.search('^alex','123alex is SB,alex is bigSB')) # print(re.match('alex','123alex is SB,alex is bigSB')) # l='egon:18:male'.split(':') # print(l) # l1=re.split('[ :/-]','a-b/c egon:18:male xxx') # print(l1) # print(re.sub('[a-z]+xx','yxp','lxx is good,sb is lllxx wxx is good cxx is good')) # [a-z]+xx pattern=re.compile('alex') print(pattern.findall('alex is SB,alex is bigSB')) print(pattern.search('alex is SB,alex is bigSB'))