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

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

##</code><code>##

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