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Date: Sun, 5 Jun 2005 22:27:51 +0200 (CEST)
To: Johannes Schlueter <johannes@php.net>
cc: internals@lists.php.net
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Subject: Re: [PHP-DEV] incrementing boolean values
From: derick@php.net (Derick Rethans)

On Sun, 5 Jun 2005, Johannes Schlueter wrote:

> Hi,
> 
> PHP is a weak-typed language which casts in the background as required - at 
> least most of the time. I recently found an exception which bugged me:
> 
>   $a = false;
>   $a++;
> 
> Here $a isn't casted to int or "incremented" to true but the incrementing has 
> no effect. By checking zend_operators.c I saw that booleans had no explicit 
> incrementing rule but uses just the default in the relevant switch.
> 
> Looking a bit deeper it got quite interesting: NULL++ gives as result the 
> integer one. This is fine for incrementing undefined variables but imho 
> inconsistent with the behavior of false. NULL-- evaluates to NULL similar to 
> false but different from NULL++.
> 
> All this makes using PHP harder than needed. At least I spent quite some time 
> finding that my variable was set to false instead of 0 (or NULL).
> 
> I wrote the attached patch which allows in-/decrementing of simple types by 
> casting bools and NULL to long. Yes, it would be a BC break but I don't think 
> someone relies on false++ being false and it would make life simpler.
> 
> Comments?

I did this a year or so ago, and after discussing with Andi we decided 
not to promote types in this case.

Derick

-- 
Derick Rethans
http://derickrethans.nl | http://ez.no | http://xdebug.org