is_null problem

[jalperin]

I'm trying to check a $_SESSION variable and if it's NULL, to set it to a value from a mySQL query. Here's the code fragment:

if  (is_null($_SESSION['nl_id']) )
    $_SESSION['nl_id'] = $row_lists['id'];

When I run it, $_SESSION['nl_id'] is NULL (I checked it with the Zend Studio debugger), but my 'if' statement evaluates FALSE (again, as checked with Zend Studio debugger) so my variable assignment never happens.

Any ideas why this is happening?

--Jeff

[LordShryku]

Is it even set? There is a difference between it not being set and it being NULL....

if (!isset($_SESSION['nl_id']) || empty($_SESSION['nl_id']))

[jalperin]

It is not even set, but the PHP Manual says:

A variable is considered to be NULL if

it has been assigned the constant NULL.

it has not been set to any value yet.

it has been unset().

I thought is_null would work in this case.

--Jeff

[LordShryku]

I don't think it works like that when you're talking about arrays....

[Sxooter]

Throw an isset in front of the is_null test:

if (isset($arr['sub']) && is_null($arr['sub'])) {
  do something here;
}