Hai, Don't dereference the original array. Instead of dereference just store it in different array in the second subroutine.

use strict;

my @num = qw(1 2 3 4 5);

first();

sub first {
   print "\@num before: @num\n";
   # prints 1 2 3 4 5
   my $result = second(\@num);
   print "result: $result\n";
   print "\@num after: @num\n";
   # prints 1 2 3 4 5 6
   # But I would need it to still print
   # 1 2 3 4 5
}

sub second {
   my @num_ref = shift;

   push(@num_ref, 6);

   my $sum = 0;

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

   return $sum;
}
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