In Perl, there are 2 different kinds of hashes.

• A hash, which is defined by the % and ( ) characters - %hash = ( );
• A reference hash, which is defined with the $ and { } characters - $hash = { };

Let's say you have a reference hash named $hash and the reference hash contains a single key with a single value.

my $hash = { 'foo' => 'bar' };

Dumper can be used to display the structure of the hash.

use Data::Dumper;
print Dumper $hash;

Which should produce the following.

$VAR1 = {
          'foo' => 'bar'
        };

Here is how to print the value associated with department_key.

print "$hash->{foo} \n";

Which should print the following.

bar

White space

Let's say the hash key contains white space. In this example, there is a single white space in "foo bar".

my $hash = { 'foo bar' => 'Hello World' };

When there is white space, the key must be wrapped in single quotes.

print "$hash->{'foo bar'} \n";