io@COMP:C>cat sw.pl

use strict;
$x=1;
use warnings;

io@COMP:C>perl sw.pl

Global symbol "$x" requires explicit package name (did you forget to declare "my $x"?) at sw.pl line 2.
BEGIN not safe after errors--compilation aborted at sw.pl line 3.


io@COMP:C>cat ws.pl

use warnings;
$x=1;
use strict;

io@COMP:C>perl ws.pl

Name "main::x" used only once: possible typo at ws.pl line 2.