#!/usr/bin/perl
# line 1 w.pl
use warnings;
my $a;
print $a;

##</code><code>##

qwurx [shmem] ~> perl -c w.pl
w.pl syntax OK

##</code><code>##

qwurx [shmem] ~> perl w.pl
Use of uninitialized value $a in print at w.pl line 4.