use strict;
use warnings;

my $variable = undef;

if( undef == 0 ){
	print "undef == 0\n";
}

if( $variable == 0 ){
	print "\$variable undef == 0\n";
}

if( "" == 0 ){
	print "\"\" == 0\n";
}

if( undef eq 0 ){
	print "undef eq 0\n";
}

if( undef eq 0 ){
	print "\$variable undef eq 0\n";
}

if( undef eq "" ){
	print "undef == \"\" \n";
}

if( 0 == "0" ){
	print "0 == \"0\"\n";
}

if( 0 eq "" ){
	print "0 eq \"\"";
}

if( undef eq "" ){
	print "undef == \"\"\n";
}

if( defined ($variable) eq "" ){
	print "undef == \"\"\n";
}

exit 0;