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:

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<?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));
  
?>

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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:

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<?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";
      
?>

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Output:

False 
True


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