for (my $i=0; $i<=$#my_data;$i++)
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isn't as clear as (and no more efficient than)

        for my $i (0 .. $#my_data)
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And more specifically,

        for ($i=0; $i<=$#my_data;$i++)
        {print $my_data[$i], "\n";
        }
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can simply be written as

        for (@my_data)
        {print $_, "\n";
        }
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