check if variable is an array

RobertCraven has asked for the wisdom of the Perl Monks concerning the following question:

Wise Monks,

I need enlightenment how to figure out if a variable is an array.
Using XML::Simple, I am parsing a SwissProt XML file. My concern is about their 'accession' elements, it can be one or more:

<accession>P41933</accession>
[download]

<accession>P41932</accession>
<accession>Q21537</accession>
[download]

XML::Simple returns an array if there is more than one element and an scalar if only one.
In case of an array, I'd like to store the first element, else just the element.
Is there any way to test if a variable contains an array? Something like:

my $id;
if(@{$HRdata->{'entry'}->{'accession'}}){
   $id = $HRdata->{'entry'}->{'accession'}->[0];
}
else{
   $id = $HRdata->{'entry'}->{'accession'};
}
[download]

If of interest, the XML files can be viewed here:
http://www.uniprot.org/uniprot/P41932.xml
http://www.uniprot.org/uniprot/P41933.xml

Many thanks!

Comment on check if variable is an array Select or Download Code

Replies are listed 'Best First'.
Re: check if variable is an array by moritz (Cardinal) on Jan 31, 2009 at 18:36 UTC
If you call XML::Simple with `ForceArray => [qw(accession)]`, then it will always be an array, and you don't need such a check in your code.	[reply] [d/l]
Re: check if variable is an array by toolic (Bishop) on Jan 31, 2009 at 18:09 UTC
Did you try ref? Otherwise, show how you are calling XML::Simple methods.	[reply]
Re^2: check if variable is an array by RobertCraven (Sexton) on Jan 31, 2009 at 18:31 UTC
Perfect, thanks so much!	[reply]