#!/usr/bin/perl use Data::Dumper; use Fcntl; use AnyDBM_File; die $! unless tie %h, 'AnyDBM_File', 'test.db', O_RDWR()|O_CREAT(), 0600; undef $h{'b'}; # try to store an undef print Dumper(\%h); # empty string is stored instead print "still defined\n" if defined $h{'b'}; # we can confirm its existence: # if it's defined, it does exist # and no undefs exist there delete $h{'b'}; # delete works as expected print "does not exist\n" unless defined $h{'b'}; print Dumper(\%h); __END__ $VAR1 = { 'b' => '' }; still defined does not exist $VAR1 = {};