%data = (
'digits' => [1, 2, 3],
'letters' => ['a', 'b', 'c']
);
How can I push '4' into $data{'digits'}?
I am new to Perl. Those $, @, % symbols look weird to me; I come from a PHP background.
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1See perldoc perldata and perldoc perldsc for information on perl data structures.Ether– Ether2010-07-11 05:54:42 +00:00Commented Jul 11, 2010 at 5:54
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4 Answers
push @{ $data{'digits'} }, 4;
$data{'digits'} returns an array-reference. Put @{} around it to "dereference it". In the same way, %{} will dereference a hash reference, and ${} a scalar reference.
If you need to put something into a hash reference, i.e.
$hashref = { "foo" => "bar" }
You can use either:
${ $hashref }{ "foo2" } = "bar2"
or the arrow-notation:
$hashref->{"foo2"} = "bar2"
In a certain way, think of a reference as the same thing as the name of the variable:
push @{ $arrayref }, 4
push @{ "arrayname" }, 4
push @arrayname , 4
In fact, that's what "soft references" are. If you don't have all the strictnesses turned on, you can literally:
# perl -de 0
DB<1> @a=(1,2,3)
DB<2> $name="a"
DB<3> push @{$name}, 4
DB<4> p @a
1234
1 Comment
ysth
A non-hard reference is a symbolic reference.
For an exotic but very pleasing on the eye option take a look at the autobox::Core CPAN module.
use autobox::Core;
my %data = (
digits => [1, 2, 3],
letters => ['a', 'b', 'c'],
);
$data{digits}->push(4);
$data{digits}->say; # => 1 2 3 4
Comments
push @{ $data{digits} }, 4;
The official Perl documentation website has a good tutorial on data structures: perldsc, particularly the Hashes-of-Arrays section.
$, @ and % are known as sigils.
