NULL, the special value on PHP

The special NULL value represents a variable with no value. NULL is the only possible value of type NULL.

Note: The null type was introduced in PHP 4.

A variable is considered to be null if:

  • it has been assigned the constant NULL.
  • it has not been set to any value yet.
  • it has been unset().

Syntax

There is only one value of type null, and that is the case-insensitive keyword NULL.

<?php
$var = NULL;
?>

See also the functions is_null() and unset().