下划线不算作python中的非字母数字字符吗？

Question

import re

x = "dkvn_i45"

if re.search(r"\W", x):
  print("Yes")
else: 
  print("No")

>>> No

I'm confused as underscore is neither a number or a letter, so surely it would count as a non-alphanumerical character?

Answer 1

Docs? https://docs.python.org/3/library/re.html

\\W
Matches any character which is not a word character. This is the opposite of \\w . If the ASCII flag is used this becomes the equivalent of [^a-zA-Z0-9_] . If the LOCALE flag is used, matches characters which are neither alphanumeric in the current locale nor the underscore.

(In short: no, \\W does not match on _ )

Answer 2

In regex \\W stands for any Non-Word character. Where Non - Word Character = anything other than letter, digit or underscore .

From above statement it should also be clear that underscore is clearly treated as a alphanumeric character.