The easy method of doing this is as follows:

  my %newhash = ( %hash1, %hash2 );
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However, the above assumes that you do not have duplicate keys in your hashes as keys in hash 2 will overwrite those in hash 1. If you do have duplicate keys, you'll have to figure out what to do and compensate for that.

Alternatively, if you simply have another key/value pair to add to an existing hash, you can just assign them directly.

  $hash{ $key } = $value;
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Again, this assumes that $key does not already exist.

Cheers,
Ovid

New address of my CGI Course.
Silence is Evil

use strict;

sub put {
    my ($hash_ref, $main_key, $sub_key, $value) = @_;
    if (!exists($hash_ref->{$main_key})) {
        $hash_ref->{$main_key} = {};
    }
    $hash_ref->{$main_key}->{$sub_key} = $value;
}

sub display {
    my $hash_ref = shift;

    my ($main_key, $sub_key);

    foreach $main_key (keys %{$hash_ref}) {
        foreach $sub_key (keys %{$hash_ref->{$main_key}}) {
            print "{$main_key, $sub_key} = " . $hash_ref->{$main_key}-
+>{$sub_key}, "\n";
        }
    }
}


my $hash_ref = {};
put($hash_ref, "one", "key1", "value1");
put($hash_ref, "one", "key2", "value2");
put($hash_ref, "two", "key1", "value1");
put($hash_ref, "two", "key3", "value3");
display($hash_ref);
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Thank you that worked!!!!

Here's a test script that illustrates one approach:

#!/usr/bin/perl -w

use strict;
use Data::Dumper;

my %hash;

print Dumper(\%hash);

$hash{one}->{key1} = 'value1';
$hash{one}->{key2} = 'value2';

print Dumper(\%hash);
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Note, I never actually assigned a value to $hash{one}. When I assigned a value to $hash{one}->{key1}, Perl automatically created the hashref for me before assigning 'value1' to the key 'key1'. This automatic creation of a data structure is called autovivification.

I like to use arrows to indicate dereferencing, but they are optional (and I think they're going away in Perl 6) so these two lines are equivalent:

$hash{one}->{key1} = 'value1';
$hash{one}{key1} = 'value1';
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use strict;

sub put {
    my ($hash_ref, $main_key, $sub_key, $value) = @_;
    if (!exists($hash_ref->{$main_key})) {
        $hash_ref->{$main_key} = {};
    }
    $hash_ref->{$main_key}->{$sub_key} = $value;
}

sub display {
    my $hash_ref = shift;

    my ($main_key, $sub_key);

    foreach $main_key (keys %{$hash_ref}) {
        foreach $sub_key (keys %{$hash_ref->{$main_key}}) {
            print "{$main_key, $sub_key} = " . $hash_ref->{$main_key}-
+>{$sub_key}, "\n";
        }
    }
}


my $hash_ref = {};
put($hash_ref, "one", "key1", "value1");
put($hash_ref, "one", "key2", "value2");
put($hash_ref, "two", "key1", "value1");
put($hash_ref, "two", "key3", "value3");
display($hash_ref);
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my $hashref = $hash{'one'};
$hashref->{'key1'} = 'value1';
$hashref->{'key2'} = 'value2';
print $_,"=",$hashref->{$_},"\n" foreach keys %$hashref;
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--
hiseldl
What time is it? It's Camel Time!

Unfotunately it won't work for me. I saw some code pasted on one of the posts as follows


push (@{$data{$formname}}, {
    'type'          =>  "select",
    'field_name'    =>  $selectname,
    'value'         =>  $attr->{'value'}
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This would work for me but I don't know how to access the information. It seems like its being pushed into an array where the arrayname is the hash{key} ? How would one access this info? If I can get the answer to this, then I believe I am all set.

What you're talking about then is a hash of arrays of hashes. $data{$formname} now returns a reference to the array, and to access an individual hash table in the array you can say something like: $data{$formname}->[0]{type}. Basically, what you're doing is a hash lookup to grab the array reference pointed to by $formname, then using an array index to obtain a reference to the nested hash whose data you need to access, and then doing a normal hash lookup there on 'type'.

Hi gnangia,

the code above uses a hash slice (hence the @) to assign a value to the key $formname. The value happens to be an anonymous hash, with keys 'type', 'field_name' and 'value', and corresponding values. What happens is that a reference to said anonymous hash is pushed onto the hash slice. To access fields in this anon hash, use code such as:

$data{$formname}->{'type'};
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or:

$data{$formname}{'type'};
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Note that the above is untested and may not work (particularly the top example might need some more curlies).

Update: Never mind my rambling, I missed a pair of parentheses in your code. fever is correct in what the code is and how you access fields in it. I really must get some more sleep, or less cafeine, or both. I thought pushing stuff onto a hash slice sounded weird when I wrote it :)

CU
Robartes-

$hash{'one'}{'key2'} = "value2";
[download]