正则表达式的使用

#-*-coding:utf8-*-
import re
# from re import findall,search,S
print('hello world')
secret_code = 'feafefexxixx23fe23xxlovexxafeifvaxxyouxx32fe'
a = 'xz123'
b = re.findall('x',a)
# .类似于占位符
print(b)

a = 'xyxy123'
# *显示x的位置
b = re.findall('x*'print(b)

b = re.findall('x?'print(b)

# 。*贪心查找最多的在之间
b = re.findall('xx.*xx'？最多种的组合
c = re.findall('xx.*?xx'print(c)

需要的放在（）里，不需要的放在（）外
d = re.findall('xx(.*?)xx'print(d)

for each in d:
print(each)

s = '''sdfxxhello
xxfsdfxxworldxxasdf'''
第二行的xx变成开始的，换行符也是
e = re.findall(re.S)
# S hellon world
print(e)

对比search和findall的使用
s2 = 'asdfxxixx123xxlovexxdfd'
# group 代表了（）的个数
f = re.search('xx(.*?)xx123xx(.*?)xx'2)
print(f)

f2 = re.search(#print(f2[0][1])

#sub
s = '123abcssfasdfas123'
#  吧123之间的字符换成789
output = re.sub('123(.*?)123''123%d123'%789print(output)

# (d+)匹配数字
a = 'asdfasf1234567fasd55fas'
b = re.findall('(d+)'print(b)

import re

old_url = 'http://www.pythontab.com/html/2013/pythonhexinbiancheng001.html'
total_page = 20

f = open('test.txt''r')
html = f.read()
f.close()

# search 爬到符合的地方就会停下
# findall 则会遍历整个文档
title = re.search('<title>(.*?)</title>'re.S).group(1)
print(title)

links = re.findall('href="(.*?)"'in links:
print(each)


先抓大在抓小
# text_field = re.findall('<ul>(.*?)</ul>',html,re.S)
# the_text = re.findall('')
翻页
for i in range(21):
new_link = re.sub('pythonhexinbiancheng00d+''pythonhexinbiancheng00%d'%ire.S)
print(new_link)