I used to use

empty()

if I want to check whether variable has value. But some time ago I decided to check which of them is faster. Additionally I’ve added to test function

is_null()

. Purpose of these functions almost the same.

Test machine:

isset() vs empty() vs is_null() performance

Iterations,Millions	isset($var),sec	empty($var),sec	is_null($var),sec
1	0.1578	0.15687	0.81775
2	0.31174	0.3314	1.65696
3	0.47739	0.56433	2.44841
4	0.62813	0.64015	3.27769
5	0.78073	0.80249	4.06912
6	0.92631	0.95377	4.91195
7	1.07459	1.08981	6.02254
8	1.25033	1.2407	6.59814
9	1.38887	1.40384	7.59789
10	1.54892	1.56017	8.34764
Iterations,Millions	isset($var),sec	empty($var),sec	is_null($var),sec

The results were predictable for me, at least according to

isset()

and

empty()

. BUT i was surprised a little with

is_null()

. I supposed that this function will be slower but not in 8 times.

So, when I want to check

$val

is null, what should I use?

Iterations,Millions	is_null($var)	$var == null	$var === null
1M	0.74273	0.17821	0.16878
2M	1.50407	0.36228	0.33803
3M	2.35153	0.52707	0.50511
4M	3.0704	0.70322	0.67562
5M	3.82585	0.89502	0.84842
6M	4.60788	1.05788	1.0336
7M	5.57395	1.2263	1.19034
8M	6.26093	1.39313	1.34496
9M	7.14926	1.56232	1.51879
10M	7.70948	1.75243	1.69789
Iterations,Millions	is_null($var)	$var == null	$var === null

According to test results,

is_null()

the slower than simple comparison operators. Thus, looks like

is_null()

makes more operations undercover than comparison. If you are too curious, you can check it in source code.

empty() -

universal function that can check if var contains something. Supports arrays. Slower than

isset()

function

isset()

— the fastest one. can check if var is NOT null and set. Nothing else.

is_null()

— simply checks if var is null. nothing else, but very slow according to comparison operators that can do the same

	gettype()	empty()	is_null()	isset()	boolean : if($x)
$var = «»;	string	TRUE TRUE	FALSE FALSE	TRUE TRUE	FALSE FALSE
$var = null;	NULL	TRUE TRUE	TRUE TRUE	FALSE FALSE	FALSE FALSE
var $x;	NULL	TRUE TRUE	TRUE TRUE	FALSE FALSE	FALSE FALSE
`$var` is undefined	NULL	TRUE TRUE	TRUE TRUE	FALSE FALSE	FALSE FALSE
$var = array();	array	TRUE TRUE	FALSE FALSE	TRUE TRUE	FALSE FALSE
$var = false;	bool	TRUE TRUE	FALSE FALSE	TRUE TRUE	FALSE FALSE
$var = true;	bool	FALSE FALSE	FALSE FALSE	TRUE TRUE	TRUE TRUE
$var = 1;	int	FALSE FALSE	FALSE FALSE	TRUE TRUE	TRUE TRUE
$var = 10;	int	FALSE FALSE	FALSE FALSE	TRUE TRUE	TRUE TRUE
$var = 0;	int	TRUE TRUE	FALSE FALSE	TRUE TRUE	FALSE FALSE
$var = -1;	int	FALSE FALSE	FALSE FALSE	TRUE TRUE	TRUE TRUE
$var = «1»;	string	FALSE FALSE	FALSE FALSE	TRUE TRUE	TRUE TRUE
$var = «0»;	string	TRUE TRUE	FALSE FALSE	TRUE TRUE	FALSE FALSE
$var = «-1»;	string	FALSE FALSE	FALSE FALSE	TRUE TRUE	TRUE TRUE
$var = «test»;	string	FALSE FALSE	FALSE FALSE	TRUE TRUE	TRUE TRUE
$var = «true»;	string	FALSE FALSE	FALSE FALSE	TRUE TRUE	TRUE TRUE
$var = «false»;	string	FALSE FALSE	FALSE FALSE	TRUE TRUE	TRUE TRUE