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I have a hash defined as,

my %data = (
'wn_l' => $wn_l, 'wn_u' => $wn_u, 'wn_d' => $wn_d,
'npts' => $#spc+1, 'spc' => [@spc], 'label' => $label,
);

and I would like to extract the data in the @spc array. I tried,

my @spc = %data{'spc'};

and

my $spc = %data{'spc'};

but this results in the array being created directly in @spc[0]. I
ended up using:

my $d = $data{'spc'};
my @data = ();
push @data, @$d;

which gives me a 1dimensional array @data that I can use... the
problem is that I don't really know why this works and it looks a
little weird. Can someone explain?

Thanks.

"Jamie Smyth" <> wrote in message
news: om...
> I have a hash defined as,
>
> my %data = (
> 'wn_l' => $wn_l, 'wn_u' => $wn_u, 'wn_d' => $wn_d,
> 'npts' => $#spc+1, 'spc' => [@spc], 'label' => $label,
> );
>
> and I would like to extract the data in the @spc array. I tried,
>
> my @spc = %data{'spc'};
>

The value for key spc is a reference to an array (hash values are always
scalars). In order to access the array, you need to dereference the
reference:

my @array = @{ $data{'spc'} };

Matt

Jamie Smyth <> wrote:
> I have a hash defined as,
>
> my %data = (
> 'wn_l' => $wn_l, 'wn_u' => $wn_u, 'wn_d' => $wn_d,
> 'npts' => $#spc+1, 'spc' => [@spc], 'label' => $label,
> );
>
> and I would like to extract the data in the @spc array.


Apply "Use Rule 1" from:

perldoc perlreftut


1) pretend is is a plain array

my @spc = @data;

2) replace the _name_ with a block ...

my @spc = @{ };

3) ... that returns a reference to an array

my @spc = @{ $data{spc} };



--
Tad McClellan SGML consulting
Perl programming
Fort Worth, Texas

Matt Garrish wrote:
>
> "Jamie Smyth" <> wrote in message
> news: om...
> > I have a hash defined as,
> >
> > my %data = (
> > 'wn_l' => $wn_l, 'wn_u' => $wn_u, 'wn_d' => $wn_d,
> > 'npts' => $#spc+1, 'spc' => [@spc], 'label' => $label,
> > );
> >
> > and I would like to extract the data in the @spc array. I tried,
> >
> > my @spc = %data{'spc'};
>
> The value for key spc is a reference to an array (hash values are always
> scalars). In order to access the array, you need to dereference the
> reference:
>
> my @array = @{ $data{'spc'} };

Also, the 'npts' entry isn't required as the array in scalar context
will return the number of elements:

my $npts = @{ $data{ spc } };


John
--
use Perl;
program
fulfillment