my @a = qw(1 2 3);
my @b = qw(4 5 6);
my @c = qw(7 8 9);

my @all = ( \@a, \@b, \@c, );

for my $aref ( @all ){
    print $_ for @{ $aref };
    print "\n";
}

##</code><code>##

123
456
789

##</code><code>##

my %hash = ( a => 1, b => 2, c => 3 );
print "$hash{ a }, $hash{ b }, $hash{ c }\n";

#output: 1, 2, 3

##</code><code>##

# define the list of students per each class

my @room1_pupils = qw( steve mike melissa );
my @room2_pupils = qw( meredith alexa chris );

# create the school, and assign the student lists to each
# hash key

my %school = (
        room1 => \@room1_pupils,
        room2 => \@room2_pupils,
);

# now you can get a list of students by room name (through
# the reference)

my @students = @{ $school{ room2 } };