择一匹配符和数据集列表

 1 # 列表（[]）和 择一匹配符（|）完成相同的效果
 2 import re
 3 
 4 m = re.match(‘[xzy]‘,‘x‘)
 5 print(m.group())
 6 m = re.match(‘x|y|z‘,‘x‘)
 7 print(m.group())
 8 
 9 # 字符集列表与择一匹配符的用法，及差异
10 pattern = r‘[ab][cd]‘
11 # 匹配第一个字母是a或b,第一个字母是c或d
12 s = ‘ac‘ 
13 # <re.Match object; span=(0, 2), match=‘ac‘>
14 s = ‘ab‘
15 # None
16 m = re.match(pattern,s)
17 print(m)
18 
19 pattern = r‘ab[cd]‘
20 # 以ab开头,后面以c或d开头
21 s = ‘ab‘ # None
22 s = ‘abc‘ 
23 # <re.Match object; span=(0, 3), match=‘abc‘>
24 s = ‘abd‘
25 # <re.Match object; span=(0, 3), match=‘abd‘>
26 m = re.match(pattern,s)
27 print(m)
28 
29 pattern = ‘ab|cd‘
30 s = ‘abc‘
31 # <re.Match object; span=(0, 2), match=‘ab‘>
32 s = ‘abd‘
33 # <re.Match object; span=(0, 2), match=‘ab‘>
34 s = ‘cd‘
35 # <re.Match object; span=(0, 2), match=‘cd‘>
36 m = re.match(pattern,s)
37 print(m)