#!/usr/bin/perl
use warnings;

my($str,$empty_str,$number,$number_zero)=('Hi','',1,0);


if($str!=undef){print"\$str is defined\n"}  
if($empty_str!=undef){print"\$empty_str is defined\n"}
if($number!=undef){print"\$number is defined\n"}
if($number_zero!=undef){print"\$number_zero is defined\n"}

##</code><code>##

Use of uninitialized value in numeric ne (!=) at ./delme.perl line 7.
Argument "Hi" isn't numeric in numeric ne (!=) at ./delme.perl line 7.
Use of uninitialized value in numeric ne (!=) at ./delme.perl line 8.
Argument "" isn't numeric in numeric ne (!=) at ./delme.perl line 8.
Use of uninitialized value in numeric ne (!=) at ./delme.perl line 9.
$number is defined
Use of uninitialized value in numeric ne (!=) at ./delme.perl line 10.