http://www.perlmonks.org?node_id=622839


in reply to Subtracting Stringified Negative Numbers

You haven't been doing anything like this, have you?
$h{1, 2} = "hello";
This creates a key consisting of three characters: "1", $SUBSEP and "2". $SUBSEP has a default octal value of 034 (aka Ctrl-\).

my %h; $h{1, 2} = "hello"; $Data::Dumper::Useqq = 1; print Dumper \%h;

From perlvar:

$SUBSCRIPT_SEPARATOR $SUBSEP $; The subscript separator for multidimensional array emulation. +If you refer to a hash element as $foo{$a,$b,$c} it really means $foo{join($;, $a, $b, $c)}