Re: iterate through a hash with two keys

[MidLifeXis]

What you are doing is trying to assign a value, but not correctly. To assign $value, you could do something like this...

$hash{$_}{$label} = $value for 'a' .. 'h';

To print the value, use print, printf, or say with the same type of a structure.

[hdb]

Independent of your solution to fionbarr's question and his real intention, I have tried to correct his code in the following way:

use strict;
use warnings;

my %hash;
my $label = "label";
my $value = "value";

# this does not work !!!
@hash{ 'a'..'h' } = ( { $label => $value } ) x 9;

$hash{ 'a' }{ $label } = "newvalue";
print $hash{ 'b' }{ $label },"\n"; # is "newvalue" !!!

This results in a structure where $hash{'a'} to $hash{'h'} all point to the same hash, so changing one changes all of them.

Is there a way to have the x operator really create 9 independent hash refs? (If this is helpful here or not is a different question.)

The following code works but is too cumbersome.

use strict;
use warnings;

my %hash;
my $label = "label";
my $value = "value";

# this works !!!
@hash{ 'a'..'h' } = ( { $label => $value },
              { $label => $value },
              { $label => $value },
              { $label => $value },
              { $label => $value },
              { $label => $value },
              { $label => $value },
              { $label => $value },
              { $label => $value }, );

$hash{ 'a' }{ $label } = "newvalue";
print $hash{ 'b' }{ $label },"\n"; # is "value" !!!

[MidLifeXis]

map { { $label => $value } } 1 .. 9?

What you are doing is creating the hashref, and duplicating the same hashref that number of times.

[fionbarr]

I am using xml_writer and I want to do this: for ('a' .. 'c') { $xml_writer->dataElement("LastName" => $t{A}{LastName}); } where the hash was filled by $t{A}{LastName} = "Smith"