$ perl -e '
> use strict;
> use warnings;
> my $string;
> print qq{>$string<\n};'
Use of uninitialized value in concatenation (.) or string at -e line 5.
><
$ perl -e '
> use strict;
> use warnings;
> my $string = q{};
> print qq{>$string<\n};'
><
$