"""
re模块中的模式常量:
A = 0
ASCII = 0
DEBUG = 0
I = 0
IGNORECASE = 0
L = 0
LOCALE = 0
M = 0
MULTILINE = 0
S = 0
DOTALL = 0
X = 0
VERBOSE = 0
U = 0
UNICODE = 0
T = 0
TEMPLATE = 0
"""
import re
re.A
re.ASCII
re.DEBUG
re.S
re.DOTALL
re.X
re.VERBOSE
re.M
re.MULTILINE
re.I
re.IGNORECASE
re.U
re.UNICODE
str_test = "ab中"
# w: 匹配大小写字母数字_: 如果是unicode的情况，它可以匹配中文
pattern = "w+"
match_obj = re.match(pattern, str_test)
print(match_obj)
# re.A = = re.ASCII
match_obj = re.match(pattern, str_test, flags=re.A)
print(match_obj)
str_test = "xxx"
pattern = "x"
# re.DEBUG： 打印调试信息
match_obj = re.match(pattern, str_test, flags=re.DEBUG)
# re.I == re.IGNORECASE 忽略大小写
str_test = "AcBd" #ABCD
pattern = "acbd"
match_obj = re.match(pattern, str_test)
print(match_obj)
match_obj = re.match(pattern, str_test, re.I)
print(match_obj)
# re.S == re.DOTALL
# 正则表达式中.字符：匹配任意一个字符，但不包括换行"n"
# re.S 匹配任意一个字符，也包括换行"n"
str_test = "ABcdn"
pattern = "....."
match_obj = re.match(pattern, str_test)
print(match_obj)
match_obj = re.match(pattern, str_test, re.S)
print(match_obj)
