PHP Functions Essential Reference

is_null

bool is_null(mixed value) 

Tests whether a value is NULL .

Returns:

TRUE if the value is NULL; FALSE otherwise

Description:

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

Availability:

UNIX, Windows

Version:

4.0.4+

See also:

gettype() 

Examples:

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');

Test whether a few different values are NULL

<pre> <?php // 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) ...