#!/usr/bin/perl
use strict;
use warnings;

my @array = qw/austria bermuda canada denmark england france germany/;

for my $country (@array)
{
  print "$country\n";

  $country = "old_" . $country;
}

# WOW!!!
# When we modified the variables above we were actually modifying the data in the original list

for my $country (@array)
{
  print "$country\n";
}

# note foreach and for keywords are identical