I want to preserve the value of the original array @num after the operation at second. What is the best way to do that?
Just take a copy of it in your second sub and work on that. For example: 
sub second {
   my $num_ref = shift;
    my @copy_of = @$num_ref;
   push(@copy_of, 6);

   my $sum = 0;

   foreach (@copy_of) {
      $sum += $_;
   }

   return $sum;
}

[download]
Cheers,
Darren :)

In reply to Re: Preserve the value of original array by McDarren
in thread Preserve the value of original array by Anonymous Monk

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