#!/usr/bin/perl use strict; use warnings; my %foo; $foo{bar} = "key bar's value"; if(exists($foo{qux})) { print "\$foo{qux} exists"; } if(ref $foo{bar} eq 'HASH' && exists($foo{bar}{baz})) { print "\$foo{bar}{baz} exists\n"; } if(exists($foo{bar})) { print "\$foo{bar} popped into existence\n"; }