PHP - is_null() Function

Definition and Usage

The function is_null() checks whether the variable is null.

Syntax

bool is_null ( mixed $value )

Parameters

Return Values

This function returns true if value is null, false otherwise.

Dependencies

PHP 4.0.4 and above.

Example

Following example demonstrates return values with different types of variables −

<?php
   $a = NULL;
   echo "a is "; var_dump(is_null($a)); echo "<br>";

   $b = true;
   echo "b is "; var_dump(is_null($b)); echo "<br>";

   $c = false;
   echo "c is "; var_dump(is_null($c)); echo "<br>";

   $d = 0;
   echo "d is "; var_dump(is_null($d)); echo "<br>";

   $e = 1;
   echo "e is "; var_dump(is_null($e)); echo "<br>";

   $f = '';
   echo "f is "; var_dump(is_null($f)); echo "<br>";

   $g = "\0";
   echo "g is "; var_dump(is_null($g)); echo "<br>";

   $h = "unset";
   echo "h is "; var_dump(is_null($g)); echo "<br>";
?>

Output

This will produce following result −

a is bool(true)
b is bool(false)
c is bool(false)
d is bool(false)
e is bool(false)
f is bool(false)
g is bool(false)
h is bool(false)

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