How to Check If a Variable is Null in PHP

09/07/2021

Contents

In this article, you will learn how to check if a variable is null in PHP.

PHP is_null() Function

The is_null() function is a language construct that can be used to determine if a variable is equal to null. It returns true if the variable is null, and false otherwise.

Syntax:
bool is_null ( mixed $var )
Parameters:
$var: The variable to be tested.
Example:
<?php
  $variable = null;

  if (is_null($variable)) {
    echo "The variable is null";
  } else {
    echo "The variable is not null";
  }
?>

This will output: The variable is null.

The comparison operator (===)

You can also check if a variable is null in PHP using the comparison operator ===:

<?php
  if ($variable === null) {
    // do something
  }
?>

Using the comparison operator === allows you to check if a variable is equal to null, including its type, which must be exactly null.

It’s important to use the === operator or is_null function to check for null, rather than using ==, because == performs type coercion and may give unexpected results. For example, 0 == null is true, while 0 === null is false.

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