By using the is_null function, we can check whether the variable is NULL or not. This function was introduced in PHP 4.0.4.
bool is_null ( mixed $var )
| Parameter | Description | Is compulsory |
|---|---|---|
| var | The variable being evaluated. | compulsory |
The PHP is_null() function returns true if var is null, otherwise false.
We can unset the variable value by using the unset function.
<?php
$var1 = TRUE;
if (is_null($var1))
{
echo 'Variable is NULL';
}
else
{
echo 'Variable is not NULL';
}
?>
<?php $x= 100; unset($x); echo is_null($x); ?>
<?php
$x = NULL;
$y = "\0";
is_null($x) ? print_r("True\n") : print_r("False\n");
echo "<br/>";
is_null($y) ? print_r("True\n") : print_r("False\n");
?>
