正则表达式，re模块-白红宇

正则表达式，re模块

阅读量：6709 次

发布时间：2019-06-25

本文共 5538 字，大约阅读时间需要 18 分钟。

一，正则表达式

　　正则表达式是对字符串操作的一种逻辑公式，我们一般使用正则表达式对字符串进行匹配和过滤，使用正则的优缺点，我们可以去http://tool.chinaz.com/regex/进行测试。

　　优点：灵活，功能性强，逻辑性强

　　缺点：上手难，一旦上手，使用起来很方便

　　正则表达式由普通字符和元字符组成，普通字符包含大小写字母，数字，在匹配普通字符的时候我们直接写就好，比如‘abc’匹配的就是‘abc’。元字符才是正则表达式的灵魂。

　　1，字符组：字符组很简单，用[]括起来，在[]中出现的内容会被匹配，例如[abc]匹配a或b或c，如果字符组中的内容过多还可以使用-，例如[a-z]匹配a到z之间的所有字母，[0-9]匹配所有阿拉伯数字

　　2，简单元字符

　　3，量词

　　4，惰性匹配和贪婪匹配

　　5，分组

　　6，转义

二，re模块

三，实例一，用re和urllib爬电影下载地址，我爬的是电影天堂小片网的电影（中间一大段if，elif只是排除编码有问题电影）　

from urllib.request import urlopen import re for i in range(1,302):     if i ==1:         url='https://www.dy2018.com/html/gndy/dyzz/index.html'     else:         url='https://www.dy2018.com/html/gndy/dyzz/index_%s.html'%i     print(url)     f1 = open('move.txt', mode='a', encoding='utf-8')     f1.write(url + '\n')     f1.close()     content=urlopen(url).read().decode('gbk')     if i==51:         obj = re.compile(r' .*?.*?a href="/(?P
    
     .*?)".*?">(?P
     
      .*?)', re.S)     else:         obj = re.compile(r'.*?a href="/(?P
      
       .*?)".*?">(?P
       
        .*?)
        .*?)">',re.S)         ss1=obj1.search(content1)         d1['adress']=ss1.group('adress1')         f1=open('move.txt',mode='a',encoding='utf-8')         f1.write(str(d1)+'\n')         f1.close() 四，用re和urllib爬维密图片

import re from urllib.request import urlopen,urlretrieve for n in range(1,5):     if n ==1:         url2 = 'https://stock.tuchong.com/topic?topicId=49282'     else:         url2='https://stock.tuchong.com/topic?topicId=49282&page=%s&count=100'%n     content=urlopen(url2).read().decode('utf-8')     obj=re.compile(r'"imageId":"(?P
    
     .*?)"',re.S)     ss=obj.finditer(content)     i=(n-1)*100+1     for el in ss:         num=el.group('bianhao')         if num=='525558981780570122'or num=='525569719200382978':             continue         elif num=='525589673617915918'or num=='525563551629443081':             continue         elif num == '525571411419332618'or num == '525585163906711562':             continue         elif num == '525554334627135503'or num == '525554274497593347':             continue         elif num == '525555872228048910'or num == '525555889405689865':             continue         elif num == '525566472207728651'or num == '525569650482741255':             continue         elif num == '525571420010053640'or num == '525571196669132802':             continue         elif num == '525571239618281484'or num == '525575964084666381':             continue         elif num == '525577347064528914'or num == '525580594059804675':             continue         elif num == '525592946387451916'or num == '525602292234190873':             continue         elif num == '525551036092645412'or num == '525552685360087057':             continue         elif num == '525554300266217477'or num == '525555657477062662':             continue         elif num == '525557349694570506'or num == '525557418413522955':             continue         elif num == '525575757924401164'or num == '525585146722910211':             continue         elif num == '525591194036862980'or num == '525594604244828160':             continue         elif num == '525619248767172615'or num == '525546397526392859':             continue         elif num == '525547952305733639'or num == '525549618751864836':             continue         elif num == '525552539333034011'or num == '525560631049584650':             continue         elif num == '525561910952460294'or num == '525577252573020167':             continue         elif num == '525577390015905802'or num == '525578919019806730':             continue         elif num == '525589845421064206'or num == '525600746043736066':             continue         elif num == '525600746046750729'or num == '525600539888320533':             continue         elif num == '525636059267465227'or num == '525551070454611970':             continue         elif num == '525551173533827166'or num == '525552693952643113':             continue         elif num == '525557461366341633'or num == '525557169308041219':             continue         elif num == '525558818575613969'or num == '525559024730243078':             continue         elif num == '525560596692074509'or num == '525563345468391437':             continue         elif num == '525575809462435842'or num == '525578901843083269':             continue         elif num == '525580405077442575'or num == '525582148835344441':             continue         elif num == '525585146721337349'or  num == '525549532855926790':             continue         elif num == '525552711133822979'or  num == '525560338990235661':             continue         elif num == '525565097818193935'or num == '525566489386811399':             continue         elif num == '525569684840644622'or num == '525571239620640780':             continue         elif num == '525571316927692806'or num == '525572725675917316':             continue         elif num == '525573017733693460'or num == '525574254687682562':             continue         elif num == '525574538153689102'or num == '525575869593550849':             continue         elif num == '525594295007182858'or num == '525596004400234497':             continue         elif num == '525608305186177028'or num == '525650120992096265':             continue         elif num == '525564900245504013':             continue         s='http://p3.pstatp.com/weili/ms/%s.webp'%num         print(s)         ss=urlretrieve(s,'维密\%s.jpg'%i)         i += 1

转载于:https://www.cnblogs.com/12345huangchun/p/9971441.html

你可能感兴趣的文章