What is the data structure of this variable in perl?

Question

I am new to perl and reading a code written in perl. A line reads like this:

$Map{$a}->{$b} = $c{$d};

I am familiar with hash looking like %samplehash and accessed as $samplehash{a}="b"

but what does the above line say about what is Map actually?

Answer 1

Given these variables:

my $a = "apples";
my $b = "pears";
my %c = ("bananas" => 2);
my $d = "bananas";
my %Map;

The assignment

$Map{$a}->{$b} = $c{$d};

Results in a hash looking like this:

%Map = (
    "apples" => {
        "pears" => 2
    }
);

%Map is a hash, which after the assignment contains a hash ref through autovivification: If not already there, the inner hash ref is automatically created by Perl by accessing the element $Map{$a}->{$b} in the %Map hash.