Python学习第十三课——re(正则表达式)模块

.的用法

import re

s = 'fhsdjakaxdsancjh'
# .代表一个元素，完成模糊匹配
res = re.findall("a..x", s)  # 找到s中以a开头x结尾中间有两个元素的结果
print(res)  # ['akax']

res1 = re.findall("^f..d", s)  # ^代表只能从字符串的开头进行匹配
print(res1)  # ['fhsd']

res2 = re.findall("n..h$", s)  # $代表必须以h结尾
print(res2)  # ['ncjh']

重复匹配

# 重复匹配（*，+，?）
s1 = 'seyqindddddiznsk'
res = re.findall("ind*", s1)  # *是匹配0到无穷次 （贪婪匹配）
print(res)  # ['inddddd']

res1 = re.findall("ind+", s1)  # +是匹配1到无穷次（贪婪匹配）
print(res1)  # ['inddddd']

res2 = re.findall("ind?", s1)  # +是匹配(0,1)
print(res2)  # ['ind']

res3 = re.findall("ind{3}", s1)  # {} 表示匹配的数量
print(res3)  # ['inddd']

[]用法

# []作用
res1 = re.findall("x[yz]", "xyuuuxz")  # x与yz组合匹配
print(res1)  # ['xy', 'xz']

res2 = re.findall('x[y,z]p', 'xypisispux,pu')
print(res2)  # ['xyp', 'x,p']

res3 = re.findall('q[a-z]', 'qjksmdqb')  # [a-z]就是p于a到z里面任意一个都可以匹配
print(res3)  # ['qj', 'qb']

res4 = re.findall('q[0-9]*', 'q988jsjjsjksjkd9')
print(res4)  # ['q988']

# [^] 非

res1 = re.findall('q[^a-z]*', 'q213')  # ^在[]中就是“非”的意思
print(res1)  # ['q213']

res2 = re.findall('q[^a-z]*', 'qabc')  # ^在[]中就是“非”的意思
print(res2)  # ['q'] 没有匹配到

用法

# (反斜杠):让有意义的变为无意义，让无意义变为有意义
'''
d 匹配任何十进制数；它相当于[0-9]
D 匹配任何非数字字符；它相当于[^0-9]
s 匹配任何空白字符；它相当于[	
fv]
S 匹配任何非空白字符；它相当于[^	
fv]
w 匹配任何字母数字字符；它相当于[a-zA-Z0-9]
W 匹配任何非字母数字字符；它相当于[0-9]
 匹配一个特殊字符边界，比如空格，&，#等
'''
res1 = re.findall('d+', "sada55578dsdsa")
print(res1)  # ['55578']

res2 = re.findall('D+', "sada55578dsdsa")
print(res2)  # ['sada', 'dsdsa']

res3 = re.findall('s+', "hellow world")
print(res3)  # [' ']

res4 = re.findall('S+', "hellow world")
print(res4)  # ['hellow', 'world']

res5 = re.findall('w+', "dasd-sh11+")
print(res5)  # ['dasd', 'sh11']

res6 = re.findall('W+', "dasd-sh11+")
print(res6)  # ['-', '+']
# 让元字符变得无意义例子

res7 = re.findall('www*baidu', 'www*baidu')
print(res7)  # ['www*baidu']

# res8 = re.findall('(84', '(84') # 报错
# print(res8)

res8 = re.findall('(84', '(84')
print(res8)  # ['(84']