#!/usr/bin/perl
use warnings;
use strict;

my $x = undef;
print "asdwf\n";
print "n,zxncv\n";
print "$x\n";

=Prints
Use of uninitialized value $x in concatenation (.) or string at C:\Projects_Perl\demounbuffer.pl line 8.
asdwf
n,zxncv
=cut

$|=1;
$x = undef;
print "asdwf\n";
print "n,zxncv\n";
print "$x\n";

=Prints
asdwf
n,zxncv
Use of uninitialized value $x in concatenation (.) or string at C:\Projects_Perl\demounbuffer.pl line 20.
=cut