What is the difference between empty function and post null in PHP?

empty() determines whether an array or a variable is empty or not. is_null() is used for checking whether a variable is null or not .is_null() will return Boolean values(TRUE or FALSE).

But If we use empty() for checking a variable having value 0 ,it will return empty. But for is_null() will return FALSE.

<?php
$a=null;
if(is_null($a)) echo "value is not there";
else echo "value is there";

?>
Output  : value is not there

<?php
$a=0;
if(is_null($a)) echo "value is not there";
else echo "value is there";
?>
Output  : value is there

<?php
$a=0;
if(empty($a)) echo "value is not there";
else echo "value is there";
?>
Output  : value is not there