Question

Im almost newbie in Perl. So just wondering about the differences between two ways of accessing a value in nested hash.

Consider the following hash:

my %hsh = ( 
    'fruits' => { 
        'red'    => 'apple', 
        'yellow' => 'banana', 
    },
    'veg' => {
        'red'    => 'capcicum',
        'yellow' => 'lemon',
    },
);

#way 1
print $hsh{'fruits'}{'red'}; 

#way 2
print $hsh{'fruits'}->{'red'};

Both has same output apple. But what is the difference between these two ways?

Answer 1

The -> operator is used to de-reference a hash or array reference. In your case, it is not needed, because Perl assumes de-referencing when dealing with a multidimension data structure. However in other cases, it is necessary:

my $ref = [ 'a','b','c' ];

print $ref[0];    #Fails
print $ref->[0];  #Succeeds