#!perl -w
use strict;

my $oero = "0E0";
my $zero = "0";

print "oero ($oero) true\n" if($oero);
print "oero ($oero) defined\n" if(defined($oero));

print "zero ($zero) true\n" if($zero);
print "zero ($zero) defined\n" if(defined($zero));

print "zero eq oero\n" if ($oero eq $zero);
print "zero == oero\n" if ($oero == $zero);

print "oero+1: ", $oero+1, "\n";
print "oero+zero: ", $oero+$zero, "\n";
print "oero+oero: ", $oero-$oero, "\n";

OUTPUT:
oero (0E0) true
oero (0E0) defined
zero (0) defined
zero == oero
oero+1: 1
oero+zero: 0
oero+oero: 0