Perl: Using data from an anonymous hash - bash

Question

I am adding on to another developers code, we are both new to perl I am trying to take a list of IPs and run it through whois. I am unsure how to access the data in the anonymous hash, how do I use it?
He told me the data was stored inside one. This is the only instance I could find mentioning a hash:
## Instantiate a reference to an anonymous hash (key value pair)
my $addr = {};

Answer 1

The anonymous hash is the {} part. It returns a reference which can be stored in a scalar variable, like in your example:
my $addr = {};
To see the structure, you can print it with Data::Dumper:
use Data::Dumper;
print Dumper $addr;
It might show you something like:
$VAR1 = {
'c' => 1,
'a' => 2
};
You access the hash keys using the arrow operator:
print $addr->{"a"}
Like how you would access a regular hash, but with the arrow operator in between.
You can dereference the reference by putting a hash sigil in front
%$addr
# compare %addr %$addr
# hash hashref dereferenced

Answer 2

Here is an anonymous hash:
my $anon_hash = {
key1 => 'Value 1',
key2 => 'Value 2',
key3 => 'Value 3',
}
If you want to access an individual value:
my $value = $anon_hash->{key1};
say $anon_hash->{key2};
If you want to update an individual value:
$anon_hash->{key3} = 'New value 3';
If you want to add a new key/value pair:
$anon_hash->{key4} = 'Value 4';
You can also use all of the standard hash functions (e.g. keys()). You just need to "deference" your hash reference - which means putting a '%' in front of it.
So, for example, to print all the key/value pairs:
foreach my $key (keys %$anon_hash) {
say "$key : $anon_hash->{$_}";
}