is_null($x) vs $x === null in PHP

is_null() Function

This is_null() function is an inbuilt function in PHP which is used to find whether a variable is NULL or not. It returns True if the given variable is null, otherwise return False.

Syntax:

bool is_null( $var )

Example 1:

<?php
// PHP program to illustrate
// is_null() function

// Declare variable and initialize it
$x = NULL;
$y = 15;

// Use is_null() function and
// display the result
var_dump(is_null($x));

var_dump(is_null($y));

?>

Output:

bool(true)
bool(false)

$x === null

It is an identical comparison operator and it returns true if the value of $x is equal to NULL. Null is a special data type in PHP which can have only one value that is NULL. A variable of data type NULL is a variable that has no value assigned to it. Any variable can be empty by setting the value NULL to the variable.

Syntax:

$var === null

Example:

<?php
// PHP program to demonstrate
// === operator

// Declare variable and initialize it
$x = "GeeksforGeeks";

if ($x === null)
    echo "True \n";
else
    echo "False \n";

// Declare variable and initialize it
$y = NULL;

if ($y === null)
    echo "True";
else
    echo "False";

?>

Output:

False 
True