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Bug #19229 isset() handles NULL values incorrectly
Submitted: 2002-09-04 07:06 UTC Modified: 2002-09-04 09:32 UTC
From: flying at dom dot natm dot ru Assigned:
Status: Not a bug Package: Scripting Engine problem
PHP Version: 4.2.2 OS: Windows 2000
Private report: No CVE-ID: None
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From: flying at dom dot natm dot ru
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 [2002-09-04 07:06 UTC] flying at dom dot natm dot ru 
Take a look at the following example:
<?php
$array = array('foo',null,'bar');
foreach($array as $key=>$value)
    echo "Set: ".((isset($array[$key]))?'yes':'no')."\nValue: ".serialize($value)."\n\n";
?>

It returns following result:

Set: yes
Value: s:3:"foo";

Set: no
Value: N;

Set: yes
Value: s:3:"bar";

 As you can see - isset() returns FALSE for array item, containing NULL value, but it should return TRUE because array item itself is set and have value.

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 [2002-09-04 07:18 UTC] cynic@php.net 
this is one of a few *very* controversial bugs/features (choose your flavor) in php. as much as lots of people would like this changed, it won't be.
use array_key_exists() for arrays, and i wish you luck with scalars. :)
 [2002-09-04 07:24 UTC] flying at dom dot natm dot ru 
Hmm... I wonder about what (really serious) reason can be for keep it as it is now? 
 And it works in this way not only with arrays, usual variables, containing NULLs are also "not set"....
 [2002-09-04 07:57 UTC] cynic@php.net 
ask rasmus. he'll tell you why this is the One True isset() Behavior. :)
 [2002-09-04 09:32 UTC] sniper@php.net 
There's nothing to fix as this is not any bug -> bogus.
 
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