python正则表达式从字符串中查找子字符串

Question

我有一个字符串:

 <robot generated="20170330 17:19:11.956" generator="Robot 3.0.2 (Python 2.7.13 on win32)">

我想获取“generated”的值，但是下面的代码不起作用

import re
doc=r'<robot generated="20170330 17:19:11.956" generator="Robot 3.0.2 (Python 2.7.13 on win32)">'
match = re.match(r'generated="(\d+ \d+:\d+:\d+.\d+)',doc)

match的值为none。谁能帮忙？

Answer 1

re.match仅匹配字符串的开头。使用 re.search相反，它不仅在开头匹配，而且在任何地方都匹配。

>>> import re
>>> doc=r'<robot generated="20170330 17:19:11.956" generator="Robot 3.0.2 (Python 2.7.13 on win32)">'
>>> re.search(r'generated="(\d+ \d+:\d+:\d+\.\d+)',doc)
<_sre.SRE_Match object at 0x1010505d0>

>>> re.search(r'generated="(\d+ \d+:\d+:\d+\.\d+)',doc).group()
'generated="20170330 17:19:11.956'

>>> re.search(r'generated="(\d+ \d+:\d+:\d+\.\d+)',doc).group(1)
'20170330 17:19:11.956'

参见 search() vs. match() from re module documentation