stupid SESSIONS question...

grudz

Hi,

I did some searching for my question, my never came up with a definitive answer, It's a little question anyway....what does this mean?

!$_SESSION

the exclamation? is it the same as isset?

thank you

travelbuff

! means "is not" or "does not"

So: if ($var != 'foo') means "if $var does not equal foo"

And: if (!$_session['var']) means "if var is not registered in the session"

You might take a look at:
http://us4.php.net/manual/en/language.operators.php

HTH

TheBB

(!$_SESSION['var']) takes on a boolean value (true/false)...

$SESSION['var'] (without the exclamation mark) takes on the value TRUE if $SESSION['var'] is set, and contains a value that evaluates to true, e.g. anything that doesn't evaluate to false.
$SESSION['var'] (without the exclamation mark) evaluates to FALSE if $SESSION['var'] is NOT set, OR if it is and contains a value that evaluates to false, e.g.: false, 0, 0.0, '', '0' or NULL.

The exclamation mark means logical negative, so !$x evaluates to TRUE if $x evaluates to FALSE and vice versa.

So, in conclusion...

!$SESSION['var'] (with exclamation mark) is TRUE if $SESSION['var'] is NOT set, OR if it is and contains a value that evaluates to false. Otherwise, !$_SESSION['var'] evaluates to FALSE.

LordShryku

Though technically, saying if(!$SESSION['var']) is the wrong way of doing it, and if it's not set, will give you an error of E_NOTICE. You should be using [man]isset[/man] or [man]empty[/man] to check. So instead, you should say if(empty($SESSION['var'])) or if(!isset($_SESSION['var'])).