How to check whether a variable is null in PHP

Use the PHP is_null() function

You can use the PHP is_null() function to check whether a variable is null or not.

Let's check out an example to understand how this function works:

<?php
$var = NULL;
 
// Testing the variable
if(is_null($var)){
    echo 'This line is printed, because the $var is null.';
}
?>

The is_null() function also returns true for undefined variable. Here's a example:

<?php
// Testing an undefined variable
if(is_null($inexistent)){
    echo 'This line is printed, because the $inexistent is null.';
}
?>