regex - Python正则表达式非贪婪

Question

正如我们所知的蟒蛇'？量词被认为是一个惰性量词，然后应该给我们最短的匹配，但在我的例子中，我得到的是第二个匹配（second_occurrence），而不是第一个匹配（first_occurrence）

content = "this is how we want that first_occurrence over there but that second_occurrence it is 
always wrong when "
match = re.search(r"^this .* that (?P<occurrence>.*?) ", content)
print(match.groupdict())

标签： regexpython-3.x

Answer 1

在你的表达"^this .* that (?P<occurrence>.*?) "中，第一个.*是贪婪的，所以它会一直匹配到最后一个that。

将您的示例更改为：

import re

content = "this is how we want that first_occurrence over there but that second_occurrence it is always wrong when "
match = re.search(r"^this .*? that (?P<occurrence>.*?) ", content)
print(match.groupdict())

这打印：

{'occurrence': 'first_occurrence'}