How can I create a hash of hashes in Perl? - perl

Question

I am new to Perl. I need to define a data structure in Perl that looks like this:
city 1 -> street 1 - [ name , no of house , senior people ]
street 2 - [ name , no of house , senior people ]
city 2 -> street 1 - [ name , no of house , senior people ]
street 2 - [ name , no of house , senior people ]
How can I acheive this?

Answer 1

Here is an another example using a hash reference:
my $data = {
city1 => {
street1 => ['name', 'house no', 'senior people'],
street2 => ['name','house no','senior people'],
},
city2 => {
street1 => etc...
...
}
};
You then can access the data the following way:
$data->{'city1'}{'street1'}[0];
Or:
my #street_data = #{$data->{'city1'}{'street1'}};
print #street_data;

Answer 2

I found the answer like
my %city ;
$city{$c_name}{$street} = [ $name , $no_house , $senior];
i can generate in this way

Answer 3

The Perl Data Structures Cookbook, perldsc, may be able to help. It has examples showing you how to create common data structures.

Answer 4

my %city ;
If you want to push
push( #{ city{ $c_name } { $street } }, [ $name , $no_house , $senior] );
(0r)
push #{ city{ $c_name } { $street } }, [ $name , $no_house , $senior];

Answer 5

You may read my short tutorial at this answer. In short you may put reference to hash into the value.
%hash = ( name => 'value' );
%hash_of_hash = ( name => \%hash );
#OR
$hash_of_hash{ name } = \%hash;
# NOTICE: {} for hash, and [] for array
%hash2 = ( of_hash => { of_array => [1,2,3] } );
# ---^ ---^
$hash2{ of_hash }{ of_array }[ 2 ]; # value is '3'
# ^-- lack of -> because declared by % and ()
# same but with hash reference
# NOTICE: { } when declare
# NOTICE: -> when access
$hash_ref = { of_hash => { of_array => [1,2,3] } };
# ---^
$hash_ref->{ of_hash }{ of_array }[ 2 ]; # value is '3'
# ---^