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Bug #48364 unexpected isset return
Submitted: 2009-05-22 18:14 UTC Modified: 2009-05-22 19:39 UTC
From: clement dot hallet at af83 dot com Assigned:
Status: Not a bug Package: Variables related
PHP Version: 5.2.9 OS: Mac OS X 10.5.6
Private report: No CVE-ID: None
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From: clement dot hallet at af83 dot com
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 [2009-05-22 18:14 UTC] clement dot hallet at af83 dot com 
Description:
------------
Hi,

A call to the 'isset' function with a variable set to NULL returns FALSE.

As seen on a previous report bug (http://bugs.php.net/bug.php?id=6076), the return value should be TRUE.

Reproduce code:
---------------
$a = NULL;
var_dump(isset($a));

Expected result:
----------------
the return of isset($a) should be TRUE.

Actual result:
--------------
isset($a) returns FALSE

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 [2009-05-22 18:23 UTC] clement dot hallet at af83 dot com 
That bug report is void. Have seen http://fr3.php.net/manual/en/function.isset.php

Maybe a change betweens versions ?
 [2009-05-22 18:26 UTC] pajoye@php.net 
no bug > bogus :)
 [2009-05-22 18:38 UTC] clement dot hallet at af83 dot com 
Sorry for the bad status :)

Please note that because of :
 $a = NULL;
 isset($a) -> FALSE
 is_null($b) -> TRUE (a notice happend)

It's impossible to test if a variable is _set_ to NULL :/
 [2009-05-22 19:19 UTC] pajoye@php.net 
is_null
 [2009-05-22 19:39 UTC] clement dot hallet at af83 dot com 
unfortunately no, because is_null on an unsetted variable returns TRUE.

What I try to say is that's impossible to test if a variable has been set AND it has been set to NULL.

For instance :

if($whatever) {
   //case 1
   $a = NULL;
} elseif($whateverelse) {
   // case 2
   $a = new SomeThing();
} else {
   // case 3
   // do things but no set the $a variable;
}

it's impossible after that to make a difference between cases 1 and 3, because (excepting for case 2):
 isset($a) will return FALSE in both cases
 is_null($a) will return TRUE in both cases


Sorry to insist, that way may have been declared as expected. But, I would like to make it understood before to consider it has a part of php.
 
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