<?php
 
error_reporting(E_ALL);

// empty
echo "empty\n";
 
var_dump(empty($undefined));
 
$arr = array("", 0, 0.0, "0", NULL, FALSE, array());
foreach($arr as $a)
        var_dump(empty($a));
 
echo "\n";
 
// empty_str
echo "empty_str\n";
 
var_dump(empty_str($undefined));
 
$arr = array("", 0, 0.0, "0", NULL, FALSE, array());
foreach($arr as $a)
        var_dump(empty_str($a));
 
echo "\n";
 
function empty_str(&$str)
{
        return empty($str) && !(isset($str) && $str === "0");
}