PHP NULL

This tutorial will teach you about the PHP NULL type and how to determine whether or not a variable is null.

In PHP, the null value is a special type. The null type has a single value that is also null. In fact, null indicates that a variable has no value.

When you assign null to a variable, it becomes null:

<?php

$email = null;
var_dump($email); // NULL

Furthermore, when you use the unset() function to remove a variable, the variable becomes null. As an example:

<?php

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

var_dump($email); // NULL

PHP NULL and case-sensitivity

PHP keywords are not case sensitive. As a result, NULL is case-insensitive. It means that you can represent the null value with null, Null, or NULL. As an example:

<?php

$email = null;
$first_name = Null;
$last_name = NULL;

Maintaining consistency in your code is a good practise. If you use null in lowercase in one place, you should use it throughout your codebase.

Testing for NULL

The is_null() function is used to determine whether or not a variable is null. If a variable is null, the is null() function returns true; otherwise, it returns false. As an example:

<?php

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

$home = 'phptutorial.net';
var_dump(is_null($home)); // bool(false)

You can also use the identical operator === to determine whether a variable is null or not. As an example:

<?php

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

$home= 'phptutorial.net';
$result = ($home === null);
var_dump($result); // bool(false)