None of the solutions do what you asked--although they may do what you want. That's because a key can exist, yet its corresponding value is undef: 

use strict;
use warnings;
use 5.010;


my %hash = (
    'one' => undef,
);

say "The key 'one' exists" if exists $hash{one};
say "The key 'two' exists" if exists $hash{two};

--output:--
The key 'one' exists

[download]

Note that nothing prints out for the non-existent key: 'two'. Then if you do this:


$hash{one} ||= 1;
say $hash{one};

--output:--
1

[download]
you will assign 1 to a key that exists--which does not meet your stated requirement.

In reply to Re: undefined or zero: looking for an elegant solution by 7stud
in thread undefined or zero: looking for an elegant solution by Ratazong

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