sub print_both_boards {
   print "USER BOARD:";
   print_board(\@main::user_ships::user_board);
   print "COMPUTER BOARD:";
   print_board(\@main::com_ships::com_board);
}

sub print_board {
    my $ar = shift;
    print "\n   1 2 3 4 5 6 7 8 9 10\n";
    print "   --------------------\n";
    for (my $i=0; $i<@$ar; ++$i) {
        print "$main::letters::letters[$i]|";
        my @t = map { $_ eq '0' ? '-' : $_ } @{$$ar[$i]};
        print " @t\n";
   }
}