regex negation without !~

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: regex negation without !~ by imp (Priest) on May 24, 2007 at 19:23 UTC
You might find this discussion useful: Negating Regexes: Tips, Tools, And Tricks Of The Trade	[reply]
Re: regex negation without !~ by RMGir (Prior) on May 24, 2007 at 19:59 UTC
Would `/^(?!FOO)/` [download] do what you want? From the perlre description, it looks like a negative lookahead is exactly what you're looking for (pun somewhat intended...) Mike	[reply] [d/l]
Re^2: regex negation without !~ by ikegami (Patriarch) on May 25, 2007 at 02:10 UTC
Just to be clear, that doesn't work if the original expression doesn't start with `^`. `>perl -le"print 'abc' !~ /b/ ?1:0" 0 >perl -le"print 'abc' =~ /^(?!b)/ ?1:0" 1 >perl -le"print 'abc' =~ /(?!b)/ ?1:0" 1` [download] That may not be an issue in this case.	[reply] [d/l] [select]
Re: regex negation without !~ by xicheng (Sexton) on May 24, 2007 at 22:34 UTC
check this out: `perl -wle ' my @test = qw(FOO FOOBAR FOO AFOO FOO BARFOO FOOFOO FOO1); print "match: $_" for grep { /^(?!FOO$)/ } @test; ' match: FOOBAR match: AFOO match: BARFOO match: FOOFOO match: FOO1` [download] Regards, Xicheng	[reply] [d/l]
Re: regex negation without !~ by cengineer (Pilgrim) on May 24, 2007 at 19:21 UTC
`if (!($str =~ /^FOO$/)) { //do something for no match }` [download]	[reply] [d/l]
Re^2: regex negation without !~ by imp (Priest) on May 24, 2007 at 19:24 UTC
This approach won't work, as he is passing the regex to another module. The regex itself has to evaluate as false.	[reply]