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+--- Thread: Regexp that won't match anything (/thread-2434.html)
Regexp that won't match anything - Ofnuts - Mar-16-2017
Is there a regexp that can't match any string that you throw at it, including the empty string?
(no, this isn't an attempt at nerd sniping, this is for tests).
RE: Regexp that won't match anything - Larz60+ - Mar-16-2017
$a
??
RE: Regexp that won't match anything - Ofnuts - Mar-16-2017
Google? What is this? :)
RE: Regexp that won't match anything - nilamo - Mar-16-2017
Use a negative lookahead to make sure something isn't there... and then check if that thing is actually there? That way, it's impossible for the check to ever match.
>>> import re
>>> regex = re.compile(r"^(?!spam)spam")
>>> regex.match("")
>>> regex.match("spam")
>>> regex.match("eggs")
>>> regex.match("s")
>>> regex.match("m")
>>> regex.match("pam")Start-of-line character included so the regex engine doesn't scan the entire line. If it matters :p
RE: Regexp that won't match anything - Larz60+ - Mar-17-2017
Quote:Google? What is this? :)
Very interesting results.
also search $a by itself
one result: https://www.prairiehome.org/