use strict; use warnings; use Devel::Peek; { my $foo; print '$foo is ', (defined($foo) ? 'defined' : 'undef'), "\n"; Dump($foo); } print "\n\n"; { my $foo; print '$foo eq $foo: $foo is stringwise ', ($foo eq $foo ? 'equal' : 'unequal'), "\n"; Dump($foo); } print "\n\n"; { my $foo; print '$foo == $foo: $foo is numerically ', ($foo == $foo ? 'equal' : 'unequal'), "\n"; Dump($foo); }