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is_null — Tests whether a value is NULL.


bool is_null(value);
mixed value: Value or variable to test


TRUE if the value is NULL; FALSE otherwise


is_null() returns TRUEif value is NULL. If not,FALSE is returned.


PHP Version: 3+, 4+

See also



Example 1393. Test whether a single value is NULL

// Define a variable to use in testing
$test = TRUE;

is_null ($test)
    or die ('Variable $test is not NULL');

Example 1394. Test whether a few different values are NULL

// Make a list of values to test
$values = array (
    'empty string ("")' => '',
    'Zero (0)' => 0,
    'TRUE' => TRUE,
    "'Hello'" => 'Hello',
    'empty array' => array(),
    'NULL' => NULL

// Loop through the values and test whether they are objects
foreach ($values as $key => $value) {
    $is_null = is_null ($value) ? 'Yes' : 'No';

    printf ("<b>%'.-45s</b>%'.3s\n", $key, $is_null);

PHP Functions Essential Reference. Copyright © 2002 by New Riders Publishing (Authors: Zak Greant, Graeme Merrall, Torben Wilson, Brett Michlitsch). This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at The authors of this book have elected not to choose any options under the OPL. This online book was obtained from and is designed to provide information about the PHP programming language, focusing on PHP version 4.0.4 for the most part. The information is provided on an as-is basis, and no warranty or fitness is implied. All persons and entities shall have neither liability nor responsibility to any person or entity with respect to any loss or damage arising from the information contained in this book.

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