PHP null

Summary: in this tutorial, you will learn about the PHP NULL type and how to check if a variable is null or not.

Introduction to the PHP null type #

The null is a special type in PHP. The null type has only one value which is also null.  The null indicates the absence of a value for a variable.

A variable is null when you assign null to it like this:

<?php

$email = null;
var_dump($email); // NULLCode language: PHP (php)

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In addition, when you use the unset() function to unset a variable, the variable is also null. For example:

<?php

$email = '[email protected]';
unset($email);

var_dump($email); // NULLCode language: PHP (php)

PHP NULL and case-sensitivity #

PHP keywords are case-insensitive. Therefore, NULL is also case-insensitive. It means that you can use null, Null, or NULL to represent the null value. For example:

<?php

$email = null;
$first_name = Null;
$last_name = NULL;Code language: PHP (php)

It’s a good practice to keep your code consistent. If you use null in the lowercase in one place, you should also use it in your whole codebase.

Testing for NULL #

To check if a variable is null or not, you use the is_null() function. The is_null() function returns true if a variable is null; otherwise, it returns false. For example:

<?php

$email = null;
var_dump(is_null($email)); // bool(true)

$home = 'phptutorial.net';
var_dump(is_null($home)); // bool(false)Code language: PHP (php)

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To test if a variable is null or not, you can also use the identical operator ===. For example:

<?php

$email = null;
$result = ($email === null);
var_dump($result); // bool(true)

$home= 'phptutorial.net';
$result = ($home === null);
var_dump($result); // bool(false)Code language: PHP (php)

Try it

Summary #

• PHP null type has a value called null, representing a variable with no value.
• Use the is_null() function or === operator to compare a variable with null.