Beginner wrote:
On 9 Nov 2007 at 14:59, Rob Dixon wrote:
Beginner wrote:
Is it possible to make a hash slice like so
It's certainly possible, but I'm not sure why you've taken a reference
to your key and value arrays. [EMAIL PROTECTED] is a single scalar value, as is
[EMAIL PROTECTED], so you're creating a single hash element. Perl has had to
stringify the reference to @keys as Perl hash keys must be strings.
The hash value is a reference you your @vals array which contains the
values 1 through 4 as Dumper shows.
I see, scalar used where list expected.
Nope, not this time! But you used a hash slice of one element:
@[EMAIL PROTECTED] = [EMAIL PROTECTED];
is the same as
my ($k, $v) = ([EMAIL PROTECTED], [EMAIL PROTECTED]);
@hash{$k} = $v;
which is ok, but does the same thing as
$hash{$k} = $v;
How about this:
#!/bin/perl
use strict;
use warnings;
use Data::Dumper;
my @keys = qw(fe fi fo thumb);
my @valone = 1..4;
my @valtwo = 10..14;
my %hash;
@[EMAIL PROTECTED] = [EMAIL PROTECTED],@valtwo];
print Dumper(\%hash);
$VAR1 = {
'fo' => undef,
'fi' => undef,
'fe' => [
1,
2,
3,
4,
10,
11,
12,
13,
14
],
'thumb' => undef
};
Alright, that's equivalent to
my @vals = (@valone, @valtwo);
my $v = [EMAIL PROTECTED];
@[EMAIL PROTECTED] = $v;
and because there are four keys in the slice and only one value, the
trailing three get set to undef.
I can't see why you can't create a slice hows values are arrays or
why all the values are assigned to the first key.
Not a biggy. I can work around it but I'm interested to know.
Each hash element must have exactly one key and one value, but you've
got an array of four keys and a list of nine values (1, 2, 3, 4, 10,
11, 12, 13, 14). Four keys can't be paired with nine values! What do
you actually want here?
@[EMAIL PROTECTED] = (@valone, @valtwo);
pairs the first four values to the keys in the array and throws away
the remaining five.
Don't forget that a reference is a single scalar value, so both
[EMAIL PROTECTED]
and
[EMAIL PROTECTED], @valtwo]
are one scalar.
HTH,
Rob
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