Is null or empty in php?

(PHP 4, PHP 5, PHP 7, PHP 8)

empty — Determine whether a variable is empty

Description

empty(mixed $var): bool

Parameters

Variable to be checked

No warning is generated if the variable does not exist. That means empty() is essentially the concise equivalent to !isset($var) || $var == false.

Return Values

Returns true if var does not exist or has a value that is empty or equal to zero, aka falsey, see conversion to boolean. Otherwise returns false.

Examples

Example #1 A simple empty() / isset() comparison.

$var = 0;// Evaluates to true because $var is empty
if (empty($var)) {
    echo '$var is either 0, empty, or not set at all';
}// Evaluates as true because $var is set
if (isset($var)) {
    echo '$var is set even though it is empty';
}
?>

Example #2 empty() on String Offsets

$expected_array_got_string = 'somestring';
var_dump(empty($expected_array_got_string['some_key']));
var_dump(empty($expected_array_got_string[0]));
var_dump(empty($expected_array_got_string['0']));
var_dump(empty($expected_array_got_string[0.5]));
var_dump(empty($expected_array_got_string['0.5']));
var_dump(empty($expected_array_got_string['0 Mostel']));
?>

The above example will output:

bool(true)
bool(false)
bool(false)
bool(false)
bool(true)
bool(true)

Notes

Note: Because this is a language construct and not a function, it cannot be called using variable functions, or named arguments.

Note:

When using empty() on inaccessible object properties, the __isset() overloading method will be called, if declared.

See Also

• isset() - Determine if a variable is declared and is different than null
• __isset()
• unset() - Unset a given variable
• array_key_exists() - Checks if the given key or index exists in the array
• count() - Counts all elements in an array or in a Countable object
• strlen() - Get string length
• The type comparison tables

Nanhe Kumar ¶

8 years ago

/**
* @author :  Nanhe Kumar <>
* List of all empty values
**/$testCase = array(
    1 => '',
    2 => "",
    3 => null,
    4 => array(),
    5 => FALSE,
    6 => NULL,
    7=>'0',
    8=>0,

    );

foreach (

Janci ¶

13 years ago

Please note that results of empty() when called on non-existing / non-public variables of a class are a bit confusing if using magic method __get (as previously mentioned by nahpeps at gmx dot de). Consider this example:

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
?>

The result for empty($registry->notEmpty) is a bit unexpeced as the value is obviously set and non-empty. This is due to the fact that the empty() function uses __isset() magic functin in these cases. Although it's noted in the documentation above, I think it's worth mentioning in more detail as the behaviour is not straightforward. In order to achieve desired (expexted?) results, you need to add  __isset() magic function to your class:

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;
        }
    }
    public function __isset($key)
    {
        if (isset($this->_items[$key])) {
            return (false === empty($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)); // false, finally!
?>

It actually seems that empty() is returning negation of the __isset() magic function result, hence the negation of the empty() result in the __isset() function above.

steven at nevvix dot com ¶

11 years ago

When you need to accept these as valid, non-empty values:
- 0 (0 as an integer)
- 0.0 (0 as a float)
- "0" (0 as a string)

function is_blank($value) {
    return empty($value) && !is_numeric($value);
}
?>

This is similar to Rails' blank? method.

markmanning at gmail dot com ¶

3 years ago

I normally count() an array, so I wanted to see how empty() would stack up.

    $test = array();
    $test2 = array();
    for ($x = 0; $x < 1000; $x++)  $test[] = $x;$ts = microtime(true);
    for ($x = 0; $x < 100000000; $x++)
    {
        if (count($test))
        {
        }
    }

    echo

your dot brother dot t at hotmail dot com ¶

7 years ago

(experienced in PHP 5.6.3) The `empty()` can't evaluate `__get()` results explicitly, so the `empty()` statement bellow always renders true
class Juice extends Liquid{
   protected $apple;
   protected $orange;
   public function __get($name) {
      return $this->$name;
   }
   public function __construct($apple, $orange) {
      $this->apple = $apple;
      $this->orange = $orange;
   }
}

class

wranvaud at gmail dot com ¶

5 years ago

Note that if your variable only has an "end of line" (aka carriage return), PHP_EOL it is not considered as empty. Since end of lines are not always easy to spot this can be confusing.

martin dot aarhof at gmail dot com ¶

10 years ago

$str = '            ';
var_dump(empty($str)); // boolean false
?>

So remember to trim your strings first!

$str = '        ';
$str = trim($str);
var_dump(empty($str)); // boolean true
?>

Anonymous ¶

14 years ago

To add on to what anon said, what's happening in john_jian's example seems unusual because we don't see the implicit typecasting going on behind the scenes.  What's really happening is:

$a = '';
$b = 0;
$c = '0';

(int)$a == $b -> true, because any string that's not a number gets converted to 0
$b==(int)$c -> true, because the int in the string gets converted
and
$a==$c -> false, because they're being compared as strings, rather than integers.  (int)$a==(int)$c should return true, however.

Note: I don't remember if PHP even *has* typecasting, much less if this is the correct syntax.  I'm just using something for the sake of examples.

Claudio Galdiolo ¶

5 years ago

Warning: an "empty" object is NOT considered to be empty
$var = new stdClass(); // "empty" object
var_dump(empty($var)); // bool(false)
?>

I don't know if there is a standard way to test for "empty" objects, I personally use array casting:
$var = new stdClass(); // "empty" object
$var = (array) $var; // cast to empty array
var_dump(empty($var)); // bool(true)
?>

info at ensostudio dot ru ¶

1 year ago

Multiple empty():
/**
* Multiple empty().
*
* @param mixed[] $vars Variables to test
* @return bool
*/
function multi_empty(& ...$vars)
{
    // no callback is supplied, all empty values will be removed
    return array_filter($vars) === [];
}
?>
example:
$notEmptyVar = 1;
$emptyVar = null;
// $undefinedVar - not definedmulti_empty($emptyVar); // true
multi_empty($emptyVar, $undefinedVar); // true
multi_empty($notEmptyVar , $emptyVar); // false
multi_empty($notEmptyVar , $emptyVar, $undefinedVar); // false
?>

chrisdmiddleton at gmail dot com ¶

8 years ago

If you want to use empty() to evaluate an expression (not a variable), and you don't have PHP 5.5+, you can do it by wrapping the call to empty in a function, like so:
function is_empty($var) {

    return empty(

phpsort ¶

11 years ago

I'm summarising a few points on empty() with inaccessible properties, in the hope of saving others a bit of time. Using PHP 5.3.2.
class MyClass {
    private $foo = 'foo';
}
$myClass = new MyClass;
echo $myClass->foo;
?>
As expected, this gives "Fatal error: Cannot access private property MyClass::$foo".
But substitute the line
if (empty($myClass->foo)) echo 'foo is empty'; else echo 'foo is not empty';
and we get the misleading result "foo is empty".
There is NO ERROR OR WARNING, so this is a real gotcha. Your code will just go wrong silently, and I would say it amounts to a bug.
If you add two magic functions to the class:
public function __get($var) { return $this->$var; }
public function __isset($var) { return isset($this->$var); }
then we get the expected result. You need both functions.
For empty($myClass->foo), I believe PHP calls __isset, and if that is true returns the result of empty on the result of __get. (Some earlier posts wrongly suggest PHP just returns the negation of __isset).
BUT …
See the earlier post by php at lanar dot com. I confirm those results, and if you extend the test with isset($x->a->b->c) it appears that __isset is only called for the last property in the chain. Arguably another bug. empty() behaves in the same way. So things are not as clear as we might hope.
See also the note on empty() at
http://uk3.php.net/manual/en/language.oop5.overloading.php
Clear as mud!

denobasis-bozic et yahoo.com ¶

13 years ago

test if all multiarray's are empty

function is_multiArrayEmpty($multiarray) {
    if(is_array($multiarray) and !empty($multiarray)){
        $tmp = array_shift($multiarray);
            if(!is_multiArrayEmpty($multiarray) or !is_multiArrayEmpty($tmp)){
                return false;
            }
            return true;
    }
    if(empty($multiarray)){
        return true;
    }
    return false;
} $testCase = array (    
0 => '',
1 => "",
2 => null,
3 => array(),
4 => array(array()),
5 => array(array(array(array(array())))),
6 => array(array(), array(), array(), array(), array()),
7 => array(array(array(), array()), array(array(array(array(array(array(), array())))))),
8 => array(null),
9 => 'not empty',
10 => "not empty",
11 => array(array("not empty")),
12 => array(array(),array("not empty"),array(array()))
);

foreach (

tom at tomwardrop dot com ¶

14 years ago

In reply to "admin at ninthcircuit dot info",

Using str_replace is unnecessary. I would encourage the use of trim which would most likely be faster (haven't tested) and easier. Trim also takes care of other white space like line breaks and tabs. Actually, in most of the applications I code, I use a multi-dimensional array map function with trim on the Super Globals such as $_POST, $_GET and $_COOKIE as so far, there hasn't been an instance where I would want any user input to begin or end with whitespace. The good thing about doing this is that you never have to worry about 'trimming' your input which makes your code easier and more reliable (incase you forget to trim some input).

marko dot crni at gmail dot com ¶

12 years ago

Calling non existing object property, empty($object->prop), will trigger __isset(), the same way as isset($object->prop) does, but there is one difference. If __isset() returns TRUE, another call to __get() will be made and actual return value will be result of empty() and result of __get().

fahimcseiiuc at gmail dot com ¶

3 years ago

/*"" (an empty string)
      0 (0 as an integer)
      0.0 (0 as a float)
      "0" (0 as a string)
      NULL
      FALSE
      array() (an empty array)*/$anEmptyString = "";
empty($anEmptyString);
if(empty($anEmptyString) == TRUE){
    echo "TRUE";
} else{
    echo "FALSE";
}
echo "

aidan1103 at yahoo dot com ¶

12 years ago

empty() should not necessarily return the negation of the __isset() magic function result, if you set a data member to 0, isset() should return true and empty should also return true.  A simpler implementation of the __isset magic function would be:

public function __isset($key) {
  return isset($this->{$key});
}

I don't understand why this isn't included in stdClass and inherited by default.

mlibazisi mabandla ¶

13 years ago

in cases when "0" is not intended to be empty, here is a simple function to safely test for an empty string (or mixed variable):

function _empty($string){
     $string = trim($string);
     if(!is_numeric($string)) return empty($string);
     return FALSE;
}
?>

chris dot wisefool at gmail dot com ¶

11 years ago

Note that checking the existence of a subkey of an array when that subkey does not exist but the parent does and is a string will return false for empty.

i.e.

$params = array('search'=>'1');
empty($params['search']['filter']); # returns false
?>

This is correct, per the documentation (http://php.net/manual/en/language.types.string.php); quite a bit down the page is the Warning: "Writing to an out of range offset pads the string with spaces. Non-integer types are converted to integer." ) I didn't receive a warning but perhaps that's correct too...depends on whether the string -> integer conversion is considered "illegal": "Illegal offset type emits E_NOTICE."

(i.e. since $params['search'] is a string, the 'filter' subscript is converted to 0, so the test becomes empty($params['search'][0]), which is obviously false), but it tripped me up enough to mistakenly file a bug report (which I've since closed).

ehsmeng ¶

12 years ago

I can't use empty() in all situations because '0' is usually not considered empty to me. I did a quick benchmark over the most common ways of testing it. '' == var suffers from '' == 0 is true so that's just there for curiosity.

    $microtimeref = microtime(true);
    $a = 0;
    $b = 'asd';
    for ($i = 0; $i < 5000000; $i++)
    {
        if (0 == mb_strlen ($b))
        {
            $a++;
        }
    }
    echo "Total time 0 == mb_strlen(var): " . round(microtime(true) - $microtimeref,3) . 's
';
?>

The results:

Total time 0 == mb_strlen(var): 3.141s
Total time 0 === strlen(var): 2.904s
Total time 0 == strlen(var): 2.878s
Total time '' == var: 1.774s
Total time '' === var: 1.706s
Total time empty(var): 1.496s

Thus '' === var will be my zero length string test.

mcfogw at gmail dot com ¶

6 years ago

I'm comparing behavior of `!` and `empty()`, find an undocumented behavior here.

just like cast-to-boolean, `empty()` cares about if SimpleXML object is made from emty tags.

`empty(simplexml_load_string(''))` is TRUE

this behavior begins from php 5.1.0~7, in 5.0.x that's FALSE

proof here => https://3v4l.org/74Tc4

thomas at thomasnoest dot nl ¶

13 years ago

Note on the selfmade empty function below:

function_exists() returns false on language constructs and empty is a language construct.

paul at worldwithoutwalls dot co dot uk ¶

18 years ago

Note the exceptions when it comes to decimal numbers:

$a = 0.00;
$b = '0.00';
echo (empty($a)? "empty": "not empty"); //result empty
echo (empty($b)? "empty": "not empty"); //result not empty
//BUT...
$c = intval($b);
echo (empty($c)? "empty": "not empty"); //result empty
?>

For those of you using MySQL, if you have a table with a column of decimal type, when you do a SELECT, your data will be returned as a string, so you'll need to do apply intval() before testing for empty.

e.g.
TABLE t has columns id MEDIUMINT and d DECIMAL(4,2)
and contains 1 row where id=1, d=0.00
$q = "SELECT * FROM t";
$res = mysql_query($q);
$row = mysql_fetch_assoc($res);
echo (empty($row['d'])? "empty": "not empty"); //result not empty
?>

e dot klerks at i-bytes dot nl ¶

11 years ago

To make an empty function, which only accepts arrays, one can use type-hinting:

// emptyArray :: [a] -> Bool function emptyArray(array $xs){
return empty($xs);
}
?>

Type hinting is a good thing to use in your code, because it makes it more easy to reason about your code. Besides that, it automatically documents the code.

Greg Hartwig ¶

14 years ago

David from CodeXplorer:
>> The ONLY reason to use empty() is for code readability. It is the same as an IF/ELSE check.
>> So, don't bother using EMPTY in the real world.

This is NOT true.  empty() will not generate warnings if you're testing against an undefined variable as a simple boolean check will.  On production systems, warnings are usually shut off, but they are often active on development systems.

You could test a flag with
   if ($flagvar)  ... ?>
but this can generate a warning if $flagvar is not set.

Instead of
   if (isset($flagvar) && $flagvar)  ... ?>
you can simply use
   if (!empty($flagvar))  ... ?>

for easy readability without warnings.

rodolphe dot bodeau at free dot fr ¶

11 years ago

Be careful, if "0" (zero as a string), 0 (zero as an integer) and -0 (minus zero as an integer) return true, "-0" (minus zero as a string (yes, I already had some customers that wrote -0 into a form field)) returns false. You need to cast your variable before testing it with the empty() function :

$var = "-0";
echo empty($var);  // returns false
$var = (int) $var; // casts $var as an integer
echo empty($vat);  // returns true
?>

jmarbas at hotmail dot com ¶

17 years ago

empty($var) will return TRUE if $var is empty (according to the definition of 'empty' above) AND if $var is not set.

I know that the statement in the "Return Values" section of the manual already says this in reverse:

"Returns FALSE if var has a non-empty and non-zero value."

but I was like "Why is this thing returning TRUE for unset variables???"... oh i see now... Its supposed to return TRUE for unset variables!!!

  ini_set('error_reporting',E_ALL);
  ini_set('display_errors','1');
  empty($var);
?>

qeremy ¶

10 years ago

Simple solution for: "Fatal error: Can't use function return value in write context in ..."

function _empty($val) { return empty($val); }
?>

rkulla2 at gmail dot com ¶

15 years ago

Since I didn't like how empty() considers 0 and "0" to be empty (which can easily lead to bugs in your code), and since it doesn't deal with whitespace, i created the following function:

function check_not_empty($s, $include_whitespace = false)
{
    if ($include_whitespace) {
        // make it so strings containing white space are treated as empty too
        $s = trim($s);
    }
    return (isset($s) && strlen($s)); // var is set and not an empty string ''
}
?>

Instead of saying if (!empty($var)) { // it's not empty } you can just say if (check_not_empty($var)) { // it's not empty }.

If you want strings that only contain whitespace (such as tabs or spaces) to be treated as empty then do: check_not_empty($var, 1)

If you want to check if a string IS empty then do: !check_not_empty($var).

So, whenever you want to check if a form field both exists and contains a value just do: if (check_not_empty($_POST['foo'], 1))

no need to do if (isset() && !empty()) anymore =]

EllisGL ¶

14 years ago

Here's what I do for the zero issue issue:
if($val == '' && $val !== 0 && $val !== '0')

Lukas ¶

4 months ago

// Difference of empty() vs. isset()$testCase = array(
    1 => '',
    2 => ' ',
    3 => null,
    4 => array(),
    5 => false,
    6 => true,
    7 => '0',
    8 => 0,
);

foreach (

GazetteSDF ¶

4 years ago

For the verification of a form, to "block" entries such as a simple space or other, I thought of this combination:

function isEmpty($string){
    $val = preg_replace('#[^A-Za-z0-9]+#', '', $string) ;
    $val = trim($string, '');
    return ($string=='') ;
}

This protects entries like: ' ' ,'  -  ', '. - +', ... On entries like name, profession, ... it's helpful

Javier Alfonso ¶

6 years ago

If you test an element of an array (like $_POST['key]), it test if the key doesn't exist or if it exist if its value is empty and never emit a warning.

For who don't want to test what happen if passed an array element here is my test and result.

$a = array();
$b = array('key');
$c = array('key' => false);
$d = array('key' => 'La verdad nos hace libres');

echo (empty(

xzero at elite7hackers dot net ¶

5 years ago

Note that empty() will return false on null byte. Eg.

// Save to variable, so it works on older PHP versions
$null_byte = chr(0); // === \0var_dump(
    empty(null),
    empty($null_byte)
);
/**
* Results:
*
* bool(true)
* bool(false)
*/

aditycse at gmail dot com ¶

4 years ago

/**
* Used for checking empty objects/array
* @uses How to check empty objects and array in php code
* @author Aditya Mehrotra<>
*/

/**
* Empty class
*/