my @tags = map { /(.{36})\.txt$/ ? $1 : undef } @files;
should be
my @tags = map { /(.{36})\.txt$/ ? $1 : () } @files;
or else you'll end up with a bunch of undefs in @tags. 

>perl -le "print 0 + map undef, 1..2
2
>perl -le "print 0 + map { () } 1..2
0

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In reply to Re^2: How do I read files in a directory and not directories? by ikegami
in thread How do I read files in a directory and not directories? by Win

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