Hello Monks,

On my script I am deleting a value within a Hash of Hashes, but I can not delete the actual key that is associated with the value because it contains other values.

The problem appears when I am deleting the value and there are no defined values in the hash but just an empty key with not undef value but just empty.

I tried all possible ways that I could think on detecting this case so I could simply delete the key from the hash but I can not figure it out.

I found this relevant question (how to check if a hash reference is empty in perl) but it does not help on my problem.

Based on the check that I did the only solution that I could think is to create a negative check for both exist and defined but even that does evaluate as true.

Sample of code:

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my %hash = (
    key1 => 'value',
    key2 => undef,
    key3 => {},
    );

foreach my $key (qw(key1 key2 key3)) {
    print "\$hash{$key} exists: " . (exists $hash{$key} ? "yes" : "no"
+) . "\n";
    print "\$hash{$key} is defined: " . (defined $hash{$key} ? "yes" :
+ "no") . "\n";
    print "\$hash{$key} is defined and not exist: " . ((!defined $hash
+{$key} and !exists $hash{$key} ) ? "yes" : "no") . "\n";
}

__END__
$hash{key1} exists: yes
$hash{key1} is defined: yes
$hash{key1} is defined and not exist: no
$hash{key2} exists: yes
$hash{key2} is defined: no
$hash{key2} is defined and not exist: no
$hash{key3} exists: yes
$hash{key3} is defined: yes
$hash{key3} is defined and not exist: no
[download]

Can someone help me understand where I am going so wrong?