What is NULL in PHP?

NULL is a special data type in PHP that has only one value, NULL. It means “no value”. NULL is not same as 0, empty string or false.

A variable is NULL in three cases: when you assign NULL to it, when it was never created, or when you remove it with unset().

<?php
$x = "Hello PHP!";
$x = null;

var_dump($x);
var_dump(is_null($x));
var_dump(isset($x));
?>

Output:

To check for NULL use is_null() or === null. The isset() function returns false for a NULL variable.

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