How do I copy an array using a reference in Perl?

Question

If I do the following, it works fine:

print $ref->{element}->[0]->{data};

I would like to see how many references are in the array so that I can loop through them, but I am having a hard time doing that.

Here is the code I have tried, but it doesn't work:

my @array = @$ref->{element};

foreach(@array) {
    print $_->{data};
}

I get an "Not an ARRAY reference" error

You might find perldoc perldsc perldoc.perl.org/perldsc.html useful. Also, the References Quick Reference at Perlmonks is handy as well: perlmonks.org/?node_id=69927 — daotoad
– daotoad, Commented Feb 11, 2010 at 23:58

mob · Accepted Answer · 2010-02-11 21:41:58Z

8

Hashes of lists are tricky that way. @$ref->{element} gets parsed as (@$ref)->{element}, dereferencing $ref instead of $ref->{element}.

Try

my @array = @{$ref->{element}}

or

my $size = scalar @{$ref->{element}}

Gory details in perllol.

edited Feb 11, 2010 at 21:41

answered Feb 11, 2010 at 21:35

mob

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1 Comment

Brad Gilbert Over a year ago

Technically you don't need to use scalar to get the length, but I would probably leave it in.

Sinan Ünür · Accepted Answer · 2010-02-11 23:33:04Z

-2

As a general aid in debugging, give Data::Dumper a look. It's invaluable for poking about in the innards of data structures.

edited Feb 11, 2010 at 23:33

Sinan Ünür

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answered Feb 11, 2010 at 21:34

vinny

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1 Comment

Jeremey Over a year ago

I am using that, but that only tells me there is an array there (which is how i know that). Since I can access that array and print values further down, I know that isn't the issue. What I need is to be able to loop through that array.

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