Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:70961
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain tutteli.ch designates 80.74.154.78 as permitted sender)
To: <internals@lists.php.net>
Date: Thu, 2 Jan 2014 19:36:59 +0100
Message-ID: <001801cf07e9$a07af1e0$e170d5a0$@tutteli.ch>
MIME-Version: 1.0
Content-Type: text/plain;
	charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Thread-Index: Ac8H6FGKsG/kxIMaTl+WYv6LdaUt8A==
Content-Language: de-ch
Subject: NAN and INF cast to int
From: php@tutteli.ch ("Robert Stoll")

Heya,

I was quite surprised that a conversion from NAN or INF does not trigger an E_WARNING. Following some examples:

An example:
$f = NAN;      
var_dump(++$f);                 // float NAN
var_dump((float) NAN);   // float NAN 
var_dump((int) NAN);       // int -2147483648 -> what?
var_dump((bool) NAN);   // bool true -> makes sense

$f = INF;
var_dump(++$f);                         // float INF
var_dump((float) INF);             // float INF
var_dump((int) INF);                 // int 0 -> what?
var_dump((bool) INF);             // bool true -> so why int 0?
var_dump((int) (bool) INF);   // int 1


Another behaviour which I find strange is that a division by 0 yields false and not NAN:
var_dump(1.5/0) ;       // boolean false

I am aware of that introducing an E_WARNING would be somewhat a BC break but I still suggest to consider it because I
rather see it as a bug. Consider the following example:
$f = INF; //somehow INF was assigned to $f at some point
$g = $f - 1; //$g is still INF -> correct IMO
$h = (int) $g; // $i = 0; -> the value as such is ok IMO but it should trigger an E_WARNING
$i = $h - 1; //$i = -1 -> especially hard to detect if one does further calculations with such a value

Thoughts on this?

Cheers,
Robert