PHP is_null() Function

The PHP is_null() function checks whether a variable is null. The function returns true if the variable is null, otherwise it returns false.

Syntax

is_null(variable)

Parameters

variable Required. Specify the variable being evaluated.

Return Value

Returns true if variable is null, false otherwise.

Example:

The example below shows the usage of is_null() function.

<?php
var_dump(is_null(null));    //returns: bool(true)
var_dump(is_null(NULL));    //returns: bool(true)
var_dump(is_null($xyz));    //returns: bool(true)

echo "\n";

var_dump(is_null(10));      //returns: bool(false)
var_dump(is_null(10.5));    //returns: bool(false)
var_dump(is_null(1e5));     //returns: bool(false)
var_dump(is_null('xyz'));   //returns: bool(false)
var_dump(is_null(true));    //returns: bool(false)
var_dump(is_null(array())); //returns: bool(false)
?>

The output of the above code will be:

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

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

PHP Warning:  Undefined variable $xyz in Main.php on line 4

Example:

Consider one more example where this function is used to check all elements of an array if they are null or not.

<?php
$Arr = array($x, 10, 10.5, null, false, 
             NULL, "xyz", 1e3, array()); 

foreach ($Arr as $value) {
  echo "is_null(".var_export($value, true).") = ";
  var_dump(is_null($value));
}
?>

The output of the above code will be:

is_null(NULL) = bool(true)
is_null(10) = bool(false)
is_null(10.5) = bool(false)
is_null(NULL) = bool(true)
is_null(false) = bool(false)
is_null(NULL) = bool(true)
is_null('xyz') = bool(false)
is_null(1000.0) = bool(false)
is_null(array (
)) = bool(false)

PHP Warning:  Undefined variable $x in Main.php on line 2

❮ PHP Variable Handling Reference