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Re^2: Pattern matching regex problem

by Anonymous Monk
on Nov 23, 2021 at 09:05 UTC ( #11139048=note: print w/replies, xml ) Need Help??


in reply to Re: Pattern matching regex problem
in thread Pattern matching regex problem

Ok, I see the difference. So, how would I tell it to print 'case 1' if 'M' is present, and 'case 2' if it's not?

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Re^3: Pattern matching regex problem
by hippo (Bishop) on Nov 23, 2021 at 10:01 UTC

    If all you want to do is check the presence of M using tr/// then it is simple:

    #!/usr/bin/env perl use strict; use warnings; my $s='IIIIIIIIIIIIIIIIIIIIIIIIIIOOOOOSSSSS'; print "$s: " . ($s =~ tr/M/M/ ? "case1\n" : "case2\n"); $s .= 'M'; print "$s: " . ($s =~ tr/M/M/ ? "case1\n" : "case2\n");

    🦛

      Or, if you don't care about tr///:

      if ($s =~ /M/) { print "case1\n"; } else { print "case2\n"; }

        tr should be faster, though.

      tr/M// is sufficient.

        Indeed it is ... as any golfer would know. :) Speaking of which, note that y is an oddball synonym for tr -- added, not for golfers (because code golf didn't exist back then), but to entice diehard sed devotees to the new frontier of Perl. I have to give a further honourable mention to y///c -- aka Abigail's length horror -- because it's one character shorter than the prosaic length.

        Finally, note that Perl's flexibility of being able to choose your own delimiter has made tr a favourite of obfuscators (and bored golfers) ... as I remember from this amusing expression:

        ($.|y|||c|y|a|||y|e|||y|i|||y|o|||y|u|||y|y||)||print
        employed in a (non-winning) entry in the pioneering Get Even golf game of 2002.

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