PHP empty($string) return true but string is not empty

Question

<?php
$m->type = 'EVENT';
if (empty($m->type)) {
  var_dump($m->type);
}
?>

This piece of code prints

string(5) "EVENT"

How is this possible?

edit

The $m object is a plain one, with magic __set and __get that store values into a protected array.

<?php
$m->type = 'EVENT';
if ($m->type == NULL) {
  var_dump($m->type);
}
?>

The above mentioned code works as expected (it skips the if body).

Have you tried storing that string into a variable and then testing it? Like this: $string = $m->type; if(empty($string)){ //code here } — Tom
– Tom, Commented Jun 4, 2013 at 13:21
Try $someVar=$m->type; if (empty($someVar)) { var_dump($m->type); } and tell us, what you get — David Jashi
– David Jashi, Commented Jun 4, 2013 at 13:22
What is $m? (ie: what class?) This doesn't happen with a stdClass, so the type of $m is probably a pretty big factor. — cHao
– cHao, Commented Jun 4, 2013 at 13:22
Is this the only piece of the code or have you just posted a subset? If there is more, a larger context may help — fullybaked
– fullybaked, Commented Jun 4, 2013 at 13:22

usoban · Accepted Answer · 2013-06-04 13:31:25Z

11

If you're using magic getter within your class, the docs page documents a rather tricky behaviour:

<?php
class Registry
{
    protected $_items = array();
    public function __set($key, $value)
    {
        $this->_items[$key] = $value;
    }
    public function __get($key)
    {
        if (isset($this->_items[$key])) {
            return $this->_items[$key];
        } else {
            return null;
        }
    }
}

$registry = new Registry();
$registry->empty = '';
$registry->notEmpty = 'not empty';

var_dump(empty($registry->notExisting)); // true, so far so good
var_dump(empty($registry->empty)); // true, so far so good
var_dump(empty($registry->notEmpty)); // true, .. say what?
$tmp = $registry->notEmpty;
var_dump(empty($tmp)); // false as expected
?>

answered Jun 4, 2013 at 13:31

usoban

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3 Comments

brazorf Over a year ago

I think this may be what's affecting my code. I'll check it out.

Roman Over a year ago

so use empty($m = $m->type) instead of empty($m->type), and it will work correctly

usoban Over a year ago

@Roman please don't, inline assignments are classical code smell.

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