边界字符的使用

 1 import re
 2 # 匹配 qq 邮箱，5-10 位数字
 3 qq = '8782303@qq.com'
 4 # <re.Match object; span=(0, 14), match='8782303@qq.com'>
 5 qq = '8782303@qq.cn' # None
 6 # 必须限制结尾
 7 pattern = r'[1-9]d{4,9}@qq.com$' # 结尾$原生字符串
 8 v = re.match(pattern,qq)
 9 print(v)
10 
11 print('----------^开始----------')
12 s = 'hello world'
13 # s = 'python'  # None
14 pattern = r'^hello.*'
15 # <re.Match object; span=(0, 11), match='hello world'>
16 o = re.match(pattern,s)
17 print(o)
18 
19 print('-----------\b匹配单词的左边界----------')
20 pattern = r'.*ab'
21 # ab 左边界的情况
22 v = re.match(pattern,'123 abeer')
23 print(v)
24 # <re.Match object; span=(0, 6), match='123 ab'>
25 
26 print('-------------\b匹配单词的右边界----------')
27 pattern = r'.*ab'
28 s = '12345 cab'
29 o = re.match(pattern,s)
30 print(o)
31 # <re.Match object; span=(0, 9), match='12345 cab'>
32 
33 print('-------------\B匹配非单词的右边界----------')
34 pattern = r'.*abB'
35 s = '12345 abc'
36 o = re.match(pattern,s)
37 print(o)
38 # <re.Match object; span=(0, 8), match='12345 ab'>
正是江南好风景