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Bug #38979 NULL
Submitted: 2006-09-28 07:40 UTC Modified: 2006-09-28 07:50 UTC
From: killabee at bk dot ru Assigned:
Status: Not a bug Package: Scripting Engine problem
PHP Version: 4.4.4 OS: Linux Red Hat, Windows 2000
Private report: No CVE-ID: None
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From: killabee at bk dot ru
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 [2006-09-28 07:40 UTC] killabee at bk dot ru 
Description:
------------
Expresions like (NULL == 0) or (NULL == '') evaluate to TRUE. I doubt whether it is correct, but unambiguously it is inconvenient. If a variable $Var = 0 or $Var = '' then empty($Var) returns TRUE, while isset($Var) returns 
TRUE too. From the other side when $Var = NULL isset($Var) returns FALSE. From this point empty string with 0 and NULL are not the same. Moreover manual says
"Also note that a NULL byte ("\0") is not equivalent to the PHP NULL constant." So why NULL is equal to 0 and '' then?
NULL means that variable has no value in php context or in other words is unset. So, I guess that check like $Var == NULL must has the same meaning like !isset($Var).

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 [2006-09-28 07:50 UTC] tony2001@php.net 
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php
 
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