c:\@Work\Perl>perl -wMstrict -le
"use warnings FATAL => 'all';
 ;;
 my $hr = { foo => 'bar' };
 my @ra = ($hr, $hr, undef, $hr, $hr);
 ;;
 for my $hashref (@ra) {
   print qq{foo is '$hashref->{foo}'};
   }
"
foo is 'bar'
foo is 'bar'
Use of uninitialized value in concatenation (.) or string at -e line 1.