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
. In fact, null
indicates the absence of a value for a variable.
A variable is null when you assign null
to it like this:
$email = null;
var_dump($email); // NULL
Code language: HTML, XML (xml)
In addition, when you use the unset()
function to unset a variable, the variable is also null. For example:
$email = 'webmaster@phptutorial.net';
unset($email);
var_dump($email); // NULL
Code language: HTML, XML (xml)
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:
$email = null;
$first_name = Null;
$last_name = NULL;
Code language: HTML, XML (xml)
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:
$email = null;
var_dump(is_null($email)); // bool(true)
$home = 'phptutorial.net';
var_dump(is_null($home)); // bool(false)
Code language: HTML, XML (xml)
To test if a variable is null
or not, you can also use the identical operator ===
. For example:
$email = null;
$result = ($email === null);
var_dump($result); // bool(true)
$home= 'phptutorial.net';
$result = ($home === null);
var_dump($result); // bool(false)
Code language: HTML, XML (xml)
Summary
- PHP null type has a value called null that represents a variable with no value.
- Use the
is_null()
function or===
operator to compare a variable with null.