PHP Unconference Europe 2015

empty

(PHP 4, PHP 5)

emptyDetermine whether a variable is empty

Description

bool empty ( mixed $var )

Determine whether a variable is considered to be empty. A variable is considered empty if it does not exist or if its value equals FALSE. empty() does not generate a warning if the variable does not exist.

Parameters

var

Variable to be checked

Note:

Prior to PHP 5.5, empty() only supports variables; anything else will result in a parse error. In other words, the following will not work: empty(trim($name)). Instead, use trim($name) == false.

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 FALSE if var exists and has a non-empty, non-zero value. Otherwise returns TRUE.

The following things are considered to be empty:

  • "" (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)
  • $var; (a variable declared, but without a value)

Changelog

Version Description
5.5.0

empty() now supports expressions, rather than only variables.

5.4.0

Checking non-numeric offsets of strings returns TRUE.

Examples

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

<?php
$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

PHP 5.4 changes how empty() behaves when passed string offsets.

<?php
$expected_array_got_string 
'somestring';
var_dump(empty($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']));
?>

Output of the above example in PHP 5.3:

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

Output of the above example in PHP 5.4:

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.

Note:

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

See Also

add a note add a note

User Contributed Notes 38 notes

up
15
denobasis-bozic et yahoo.com
5 years ago
test if all multiarray's are empty

<?php
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 (
$testCase as $key => $case ) {
    echo
"$key is_multiArrayEmpty= ".is_multiArrayEmpty($case)."<br>";
}
?>

OUTPUT:
========

0 is_multiArrayEmpty= 1
1 is_multiArrayEmpty= 1
2 is_multiArrayEmpty= 1
3 is_multiArrayEmpty= 1
4 is_multiArrayEmpty= 1
5 is_multiArrayEmpty= 1
6 is_multiArrayEmpty= 1
7 is_multiArrayEmpty= 1
8 is_multiArrayEmpty= 1
9 is_multiArrayEmpty=
10 is_multiArrayEmpty=
11 is_multiArrayEmpty=
12 is_multiArrayEmpty=
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13
steven at nevvix dot com
3 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)

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

This is similar to Rails' blank? method.
up
8
chris dot wisefool at gmail dot com
3 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.

<?php
$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).
up
6
EllisGL
7 years ago
Here's what I do for the zero issue issue:
if($val == '' && $val !== 0 && $val !== '0')
up
7
Janci
5 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:

<?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
?>

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:

<?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;
        }
    }
    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.
up
6
rodolphe dot bodeau at free dot fr
4 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 :

<?php
$var
= "-0";
echo empty(
$var);  // returns false
$var = (int) $var; // casts $var as an integer
echo empty($vat);  // returns true
?>
up
4
martin dot aarhof at gmail dot com
2 years ago
<?php
$str
= '            ';
var_dump(empty($str)); // boolean false
?>

So remember to trim your strings first!

<?php
$str
= '        ';
$str = trim($str);
var_dump(empty($str)); // boolean true
?>
up
3
Anonymous
6 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.
up
3
tom at tomwardrop dot com
6 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 $_COOKIE as so far, there hasn't been an instance where I would want any user input to begin or end with whitespace. The good thing about doing this is that you never have to worry about 'trimming' your input which makes your code easier and more reliable (incase you forget to trim some input).
up
3
marko dot crni at gmail dot com
4 years ago
Calling non existing object property, empty($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().
up
3
phpsort
3 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.
<?php
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!
up
3
ehsmeng
4 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.

<?php
    $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): <b>" . round(microtime(true) - $microtimeref,3) . 's</b><br />';
?>

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.
up
3
e dot klerks at i-bytes dot nl
3 years ago
To make an empty function, which only accepts arrays, one can use type-hinting:

<?php
// 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.
up
3
qeremy
2 years ago
Simple solution for: "Fatal error: Can't use function return value in write context in ..."

<?php
function _empty($val) { return empty($val); }
?>
up
2
jmarbas at hotmail dot com
9 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!!!

<?php
  ini_set
('error_reporting',E_ALL);
 
ini_set('display_errors','1');
  empty(
$var);
?>
up
3
emperoruk at dontspam dot hotmail dot com
5 years ago
When using the php empty() function to check submitted variables such as $_POST or $_GET, be careful to remember that values 0 (integer) and "0" (string with zero character) are all considered empty. eg. in a simple cms a page ID of zero might be used to indicate that the homepage should be displayed but using the following code:

<?php
if (isset($_GET['pid'] && !empty($_GET['pid']) {
 
// assign value to local variable
 
$pageID = $_GET['pid'];
} else {
  echo
"missing variable 'pageID'";
}
?>

When attempting to display the homepage using a pid of zero the above code will fail.

So as a result i wrote a small function to replace the php empty() function in situations where you want 0 and "0" not to be considered empty.

<?php
function is_empty($var, $allow_false = false, $allow_ws = false) {
    if (!isset(
$var) || is_null($var) || ($allow_ws == false && trim($var) == "" && !is_bool($var)) || ($allow_false === false && is_bool($var) && $var === false) || (is_array($var) && empty($var))) {   
        return
true;
    } else {
        return
false;
    }
}
?>

This function will allow you to test a variable is empty and considers the following values as empty:

an unset variable -> empty
null -> empty
0 -> NOT empty
"0" -> NOT empty
false -> empty
true -> NOT empty
'string value' -> NOT empty
"    " (white space) -> empty
array() (empty array) -> empty

There are two optional parameters:

$allow_false: setting this to true will make the function consider a boolean value of false as NOT empty. This parameter is false by default.

$allow_ws: setting this to true will make the function consider a string with nothing but white space as NOT empty. This parameter is false by default.

In Testing:

<?php
// an unset variable
echo 'unset variable ($notset) - Empty: ';
echo
is_empty($notset) ? 'yes<br />' : 'no<br />';
// NULL variable
echo 'null - Empty: ';
$var = null;
echo
is_empty($var) ? 'yes<br />' : 'no<br />';
// integer 0
echo '0 - Empty: ';
$var = 0;
echo
is_empty($var) ? 'yes<br />' : 'no<br />';
// string "0"
echo 'string "0" - Empty: ';
$var = "0";
echo
is_empty($var) ? 'yes<br />' : 'no<br />';
// boolean value false
echo 'false - Empty: ';
$var = false;
echo
is_empty($var) ? 'yes<br />' : 'no<br />';
// allow boolean value false
echo 'false ($allow_false = true) - Empty: ';
$var = false;
echo
is_empty($var, true) ? 'yes<br />' : 'no<br />';
// boolean value true
echo 'true - Empty: ';
$var = true;
echo
is_empty($var) ? 'yes<br />' : 'no<br />';
// string
echo 'string "foo" - Empty: ';
$var = "foo";
echo
is_empty($var) ? 'yes<br />' : 'no<br />';
// white space
echo 'white space "     " - Empty: ';
$var = "    ";
echo
is_empty($var) ? 'yes<br />' : 'no<br />';
// allow white space
echo 'white space ($allow_ws = true) "     " - Empty: ';
$var = "    ";
echo
is_empty($var, false, true) ? 'yes<br />' : 'no<br />';
// empty array
echo 'empty array - Empty: ';
$var = array();
echo
is_empty($var) ? 'yes<br />' : 'no<br />';
?>

the above code outputs the following:

unset variable ($notset) - Empty: yes
null - Empty: yes
0 - Empty: no
string "0" - Empty: no
false - Empty: yes
false ($allow_false = true) - Empty: no
true - Empty: no
string "foo" - Empty: no
white space " " - Empty: yes
white space ($allow_ws = true) " " - Empty: no
empty array - Empty: yes

Hope this code is useful for someone.

Michael
up
2
paul at worldwithoutwalls dot co dot uk
10 years ago
Note the exceptions when it comes to decimal numbers:

<?php
$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
<?php
$q
= "SELECT * FROM t";
$res = mysql_query($q);
$row = mysql_fetch_assoc($res);
echo (empty(
$row['d'])? "empty": "not empty"); //result not empty
?>
up
1
thomas at thomasnoest dot nl
5 years ago
Note on the selfmade empty function below:

function_exists() returns false on language constructs and empty is a language construct.
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1
aidan1103 at yahoo dot com
4 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.
up
1
rkulla2 at gmail dot com
7 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:

<?php
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 =]
up
1
chrisdmiddleton at gmail dot com
1 month 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:
<?php
function is_empty($var) {

    return empty(
$var);

}
?>
Then you can do something like
<?php
if(is_empty(NULL)) {
/* ... */
}
?>
without issue, since the local variable $var is being tested rather than the expression in the function call itself.
up
0
turabgarip at gmail dot com
5 months ago
Checking if a variable is empty or not when you have more than one will add so many similar lines to your code; and will require re-writing of course. Like for example;

<?php
if (!empty($a))
   
$myvar = $a;
elseif (!empty(
$b))
    
$myvar = $b;
//...
?>

If, for example $myvar should be pulled among 5 vars, you need to write it for 5 times. But in the below example, using $myvar = esor($var1, $var2, ...) will set it to first non-empty var.

<?php

function esor()
{
   
$arg_num = func_num_args();
   
// "No arguments" is empty string
   
if (!$arg_num) return '';
   
$args = func_get_args();
    for (
$i = 0; $i < $arg_num; $i++)
        if (!empty(
$args[$i]))
            return
$args[$i];
   
// Not found any filled var?
   
return ''; // Empty string is what you get
}

// For example;
mail(esor($settings['admin_mail'], $_ENV['SERVER_ADMIN']), 'Something went wrong', 'Error was foo');

?>

This will make it "one line code" no matter how many vars you have to check. Hope that helps.
up
0
bharris at nospam dot epic dot com
11 months ago
XML::Unserializer produces unexpected results because empty($key) is true when $key = 0.

Example:

<?php
include("/usr/share/php/XML/Unserializer.php");
$xml= <<<EOD
<?xml version="1.0"?>
<groups _type="array">
    <XML_Serializer_Tag _originalKey="0" _type="array">
        <gid _type="integer">10</gid>
    </XML_Serializer_Tag>
    <XML_Serializer_Tag _originalKey="5" _type="array">
        <gid _type="integer">100</gid>
    </XML_Serializer_Tag>
</groups>
EOD;
$uns = new XML_Unserializer();
$res = $uns->unserialize($xml);
$recs = $uns->getUnserializedData();
print_r($recs);
?>

produces

Array
(
    [0] => Array
        (
            [gid] => 10
        )

    [5] => Array
        (
            [gid] => 100
        )
)

while

<?php
include("/usr/share/php/XML/Unserializer.php");
$xml= <<<EOD
<?xml version="1.0"?>
<groups _type="array">
    <XML_Serializer_Tag _originalKey="5" _type="array">
        <gid _type="integer">100</gid>
    </XML_Serializer_Tag>
    <XML_Serializer_Tag _originalKey="0" _type="array">
        <gid _type="integer">10</gid>
    </XML_Serializer_Tag>
</groups>
EOD;
$uns = new XML_Unserializer();
$res = $uns->unserialize($xml);
$recs = $uns->getUnserializedData();
print_r($recs);
?>

produces

Array
(
    [1] => Array
        (
            [gid] => 100
        )

    [6] => Array
        (
            [gid] => 10
        )
)

This is because the "empty" key value of 0 results in a push onto the end of the array, rather than an insertion at key position 0.
up
0
Greg Hartwig
6 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
   <?php if ($flagvar)  ... ?>
but this can generate a warning if $flagvar is not set.

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

for easy readability without warnings.
up
-1
mlibazisi mabandla
5 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):

<?php
function _empty($string){
    
$string = trim($string);
     if(!
is_numeric($string)) return empty($string);
     return
FALSE;
}
?>
up
-1
nobody at example dot com
8 years ago
Re: inerte is my gmail.com username's comment:

While that may be true, those two statements (empty($var), $var == '') are NOT the same. When programming for web interfaces, where a user may be submitting '0' as a valid field value, you should not be using empty().

<?php
    $str
= '0';

   
// outputs 'empty'
   
echo empty($str) ? 'empty' : 'not empty';

   
// outputs 'not empty'
   
echo $str == '' ? 'empty' : 'not empty';
?>
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-1
Nanhe Kumar
8 months ago
<?php
/**
* @author :  Nanhe Kumar <nanhe.kumar@gmail.com>
* List of all empty values
**/

$testCase = array(
   
1 => '',
   
2 => "",
   
3 => null,
   
4 => array(),
   
5 => FALSE,
   
6 => NULL,
   
7=>'0',
   
8=>0,
   
);

foreach (
$testCase as $k => $v) {
    if (empty(
$v)) {
        echo
"<br> $k=>$v is empty";
    }
}
/**
Output
1=> is empty
2=> is empty
3=> is empty
4=>Array is empty
5=> is empty
6=> is empty
7=>0 is empty
8=>0 is empty
**/
?>
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-2
Ed
6 years ago
Also, it doesn't appear to mention in the documentation, if a variable hasn't previously been declared, empty also returns true.

E.g.
var $bar;
empty( $bar ); // declared variable returns true.
empty( $foo ); // undeclared variable also returns true.

The closest the documentation comes to saying this is:
"var $var; (a variable declared, but without a value in a class)"
which isn't really the same, as the variable doesn't necessarily have to be declared first.
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-3
nahpeps at gmx dot de
9 years ago
When using empty() on an object variable that is provided by the __get function, empty() will always return true.

For example:

<?php
class foo {
  
   public function
__get($var) {
      if (
$var == "bar") {
         return
"bar";  
      }  
   }  
}
$object_foo = new foo();
echo
'$object_foo->bar is ' . $object_foo->bar;
if (empty(
$object_foo->bar)) {
   echo
'$object_foo->bar seems to be empty';  
}
?>

produces the following output:
$object_foo->bar is bar
$object_foo->bar seems to be empty
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-3
florian.sonner [at] t-online.de
7 years ago
Since a few people here mentioned that empty will not work with magic-overloading ("__get($var)"):

empty(..) goes the same way as isset(..) do, to check if a property exists. Thus you have to override the magic-function __isset($var) to produce correct results for empty(..) in combination with a magic-overloaded property.
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-3
serkons at yahoo dot com
4 years ago
Hi you can check the status of multiple array or any variable is empty with below code.

<?php
$microtimeref
= microtime ( true );
//$variable=null; // false,true,0,''
//$variable = array ('id' => 10, 'name' => 'serkon' );
$variable = array (array (0) );
echo
'<pre>';
function
getArray($dizi) {
    foreach (
$dizi as $value )
        return
$value;
}
function
isEmpty($array) {
    if (
is_array ( $array )) {
       
$dizi = getArray ( $array );
        if (
is_array ( $dizi ))
           
$ref = isEmpty ( $dizi );
        else
            if (
strlen ( $dizi ) >= 1)
                return
false;
            else
                return
true;
    }
    else
        if (
strlen ( $array ) >= 1)
            return
false;
        else
            return
true;
   
    if (
$ref === false)
        return
false;
    else
        return
true;
}
$sonuc = isEmpty ( $variable );
var_dump ( $sonuc );
echo
"Total time: <b>" . round ( microtime ( true ) - $microtimeref, 4 ) . 's</b><br />';
echo
'</pre>';
?>

Response:

bool(false)  // not empty
Total time: 0s
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-3
David from CodeXplorer
6 years ago
Mad Hampster did  his test wrong. empty is NOT faster than a simple boolean check. The ONLY reason to use empty() is for code readability. It is the same as an IF/ELSE check. But if you are dealing with intermediate or higher level coders this function has no other benefit.

So, don't bother using EMPTY in the real world.

I ran an array with 5000 simple true/false values through four checks (both types twice) in case of any gain one type might have by going first. These are my results generated one one page request. (PHP5)

0.015328 Time EMPTY
0.014281 Time IF/ELSE
0.015239 Time EMPTY
0.013404 Time IF/ELSE

The page was accessed a couple times to reduce caching effects.
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-4
Andrea Giammarchi
6 years ago
In addiction to Ed comment:
http://uk.php.net/manual/en/function.empty.php#80106

if an instance variable is assigned with an empty value, i.e. false, empty returns true.

<?php
class TestEmpty{
    protected          
$empty;
    public  function   
__construct(){
       
var_dump(empty($this->empty)); // true
       
$this->empty = false;
       
var_dump(empty($this->empty)); // true
   
}
}
new
TestEmpty;
?>

I think this is an expected behaviour but at the same time the note about classes variables is too ambiguous.

''var $var; (a variable declared, but without a value in a class)''

Please change them into something like:
''var $var; (a variable undeclared or declared with an empty value in a class)''
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-3
Antone Roundy
7 years ago
There's a faster and easier to write method than (isset($a) && strlen($a)) -- isset($a{0}). It evaluates to false if $a is not set or if it has zero length (ie. it's first character is not set). My tests indicate that it's about 33% faster.
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-5
MaD HamsteR
6 years ago
SAME RESULT! But somehow using empty() function is faster for about 10-13%

<?php

$array
[] = "";
$array[] = '';
$array[] = 0;
$array[] = "0";
$array[] = NULL;
$array[] = false;
$array[] = array();
$array[] = $var;

foreach(
$array as $value){
    echo (!empty(
$value))? 'Not empty!' : 'Empty!';
    echo
'<br />'."\r\n";
}

echo
'<br />'."\r\n";

foreach(
$array as $value){
    echo (
$value)? 'Not empty!' : 'Empty!';
    echo
'<br />'."\r\n";
}

?>
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-3
jay at w3prodigy dot com
6 years ago
Also note, that if you have a URI that looks like this:

/page/index.php?query=

performing isset($_GET['query']) will return TRUE. as query is set, though null, in the QUERY.

To counteract this behavior, check isset($_GET['query']) and !empty($_GET['query']) as empty will detect the null value.
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-7
christian dot achatz at adventure-php-framework dot org
3 years ago
Since this special case is not mentioned already: the empty() check does not work for mysqli resources / connections stored within a private variable.

Instead of

if(!empty($this->dbConn->error)){...}

you have to use

$error = $this->dbConn->error;
if(!empty($error)){...}

otherwise the condition will not evaluate to true in case a mysqli error is given for the present connection.
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-11
contato at andersonfraga dot net
5 years ago
<?php

function _empty() {
    foreach(
func_get_args() as $args) {
        if( !
is_numeric($args) ) {
            if(
is_array($args) ) { // Is array?
               
if( count($args, 1) < 1 ) return true;
            }
            elseif(!isset(
$args) || strlen(trim($args)) == 0)
                return
true;
            }
        }
    }
    return
false;
}

?>
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