import re

# # .  通配符，一个  .  模糊匹配一个除换行符之外的任意字符

# ret = re.findall('a..in', 'helloalvin')

# print(ret)  # ['alvin']

#

# # ^ 必须以某个字符开始

# ret = re.findall('^a...n', 'alvinhelloawwwn')

# print(ret)  # ['alvin']

#

# # $ 必须以某个字符结尾

# ret = re.findall('a...n$', 'alvinhelloawwwn')

# print(ret)  # ['awwwn']

#

# # * 贪婪匹配 [0, +oo]

# ret = re.findall('abc*', 'abcccc')  # 贪婪匹配[0,+oo]

# print(ret)  # ['abcccc']

#

# ret = re.findall('a.*n', 'alvinhelloawwwn')

# print(ret)  #  ['alvinhelloawwwn']  贪婪匹配

#

# # + 贪婪匹配 [1, +oo]

# ret = re.findall('abc+', 'abccc')  # [1,+oo]

# print(ret)  # ['abccc']

#

# ret = re.findall('a.+n', 'alvinhelloawwwn')

# print(ret)  # ['alvinhelloawwwn'] 贪婪匹配

#

# # ? 匹配[0,1]

# ret = re.findall('abc?', 'abcccffab')  # [0,1]

# print(ret)  # ['abc', 'ab']

#

# {} 自定义重复次数 {1,} 表示一到正无穷

ret = re.findall('abc{1,4}', 'abcccccsccccc')

print(ret)  # ['abcccc'] 贪婪匹配

# --------------------------------------------字符集[]

# ret = re.findall('a[bc]d', 'acd')

# print(ret)  # ['acd'] 匹配 b 或 c

#

# ret = re.findall('[a-z]', 'acd')

# print(ret)  # ['a', 'c', 'd']

#

# ret = re.findall('[.*+]', 'a.cd+')

# print(ret)  # ['.', '+']  # 在[]中，* + 失去原有的作用

#

# 在字符集里有功能的符号: - ^ \

#

# ret = re.findall('[1-9]', '45dha3')

# print(ret)  # ['4', '5', '3']

#

# ^ 放在[]表示取反，不取 a 或 b 或 ,

# ret = re.findall('[^ab,]', '45bdha3,')

# print(ret)  # ['4', '5', 'd', 'h', '3']

#

# ret = re.findall('[\d]', '45bdha3')

# print(ret)  # ['4', '5', '3']

# \ 的功能

# 1、反斜杠后面跟元字符去除其特殊功能

# 2、反斜杠后面跟普通字符实现其特殊功能

'''

\d 相当于 [0-9]

\D 相当于 [^0-9]

\s 匹配任何空白字符

\S 匹配任何非空字符

\w 匹配任何字母数字字符  [0-9a-zA-Z]

\W 匹配任何非字母数字字符  [^0-9a-zA-Z]

\b 匹配一个特殊字符边界，也就是指单词和空格间的位置

'''

# ret=re.findall('I\b','I ')

# print(ret)#[]

ret = re.findall('\dert','13ert')

print(ret)      # ['3ert']

ret = re.findall('\Dert','13^ert')

print(ret)      # ['^ert']

ret = re.findall('\s123', '')

print(ret)

print(re.findall(r'I\b', 'hello,I am a hhI$hh'))

print(re.findall(r'\bI', 'hello, I am a hhI$hh'))

print(re.findall(r'\\', r'abf\vaf'))