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

print qq{perl version: $] \n};;; 

my $x; 
my %y= ("h"=>1, "i"=>2);  

print $x, $y{x}; 
printf "%s", $x;

exit;

__END__

##</code><code>##

U:\>uninit01.pl
perl version: 5.018002
Use of uninitialized value $x in print at U:\uninit01.pl line 10.
Use of uninitialized value in print at U:\uninit01.pl line 10.
Use of uninitialized value $x in printf at U:\uninit01.pl line 11.

##</code><code>##

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

print qq{perl version: $] \n};;; 

my $x; 
my %y= ("h"=>1, "i"=>2);  

eval
{
	print $x, $y{x}; 
} ;

# Check for error out of eval{}
if ($@)
{
	# There was an error trapped.
	my $dsperr = $@;
	print "-------------------------\n";
	print "$dsperr\n";
	print "-------------------------\n";
}
else
{
	print "No error found.\n";
}

printf "%s", $x;

exit;

__END__

##</code><code>##

U:\>uninit02.pl
perl version: 5.018002
Use of uninitialized value $x in print at U:\uninit02.pl line 12.
Use of uninitialized value in print at U:\uninit02.pl line 12.
No error found.
Use of uninitialized value $x in printf at U:\uninit02.pl line 29.