Here's a golfed version of the previous solutions. 
#!/usr/bin/perl

use strict;
use warnings;

my %hash;
print %hash ? 'defined' : 'undefined';

[download]


Update: Changed keys %hash to plain old %hash, per swampyankee's post. Duh me!

In reply to Re: Defined vs. undefined by kwaping
in thread Defined vs. undefined by tamaguchi

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