How can I unset a session variable that is passed as function parameter?

[colap]

<?php    
    if(session_id() == '') {
        session_start();
    }
    $_SESSION['msg']="Updated.";
    psession($_SESSION['msg']);
    function psession($msg){
        echo $msg;
        unset($msg);
    }
?>

This doesn't unset $_SESSION['msg']. How can I unset it?

[requinix]

You can't really do it. Not like that.

 

What problem are you trying to solve? Why do you need to unset a value this way?

[colap]

I want to unset session variable from inside function which is passed as function parameter.

 

In this way:

[code

unset($_SESSION['msg']);

[/code]

[requinix]

Then that's the way you have to do it: unset whatever in $_SESSION directly. When you unset($msg) all you're doing is unsetting that variable.

[gizmola]

Ok, so first things first -- why?

 

if(session_id() == '') {
        session_start();
    }

Do you want sessions or not? If so, you should just have session_start().

 

 

$_SESSION is a super global.

 

In PHP superglobals are variables that are available everywhere and thus visible inside functions.

 

 

So, in this case, your function has little to no value in terms of the passing of a parameter. Quite frankly, it would be really bad practice to do what you were trying to do even if it did work.

 

One purpose of a functions is to hide details from the rest of the program, so setting/unsetting a variable inside a function that is otherwise global really goes against the idea of "information hiding".

[requinix]

Ok, so first things first -- why?

 

if(session_id() == '') {
        session_start();
    }

Do you want sessions or not? If so, you should just have session_start().

 

I've done that in a handful of cases where I needed sessions but wasn't sure if it had been started yet (and there wasn't anywhere that would authoritatively start them). It could be an indication of poor design, however.