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Re: Bug? Use of uninitialized value $1 in substitution iterator

by ikegami (Pope)
on Mar 04, 2009 at 15:28 UTC ( #748196=note: print w/replies, xml ) Need Help??


in reply to Bug? Use of uninitialized value $1 in substitution iterator

Perl distinguishes between a capture that wasn't encountered in the match and a capture that matched zero characters.
use Data::Dumper qw( Dumper ); '' =~ / ^ ( (?: ( bb ) # $2 )? ) # $1 $ /x; local $Data::Dumper::Useqq = 1; local $Data::Dumper::Terse = 1; local $Data::Dumper::Indent = 0; print('$1 = ', Dumper($1), "\n"); print('$2 = ', Dumper($2), "\n");
$1 = "" $2 = undef

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Re^2: Bug? Use of uninitialized value $1 in substitution iterator
by clinton (Priest) on Mar 04, 2009 at 18:29 UTC
    nicely explained

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