c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my $count;
 F();
 dd $count;
 ;;
 $count = 0;
 F();
 dd $count;
 ;;
 sub F {
   print defined $count ? '=' x ($count += 5) : 'Undefined count';
   }
"
Undefined count
undef

=====
5