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Date: Wed, 19 Feb 2020 17:05:51 +0000
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To: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Allow null variables to be decremented
From: rowan.collins@gmail.com (Rowan Tommins)

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On Wed, 19 Feb 2020 at 15:05, C=C3=B4me Chilliet <
come.chilliet@fusiondirectory.org> wrote:

>
> Is ++$a behaving differently than $a++ for NULL/FALSE/TRUE?
>


The actual implementation of incrementing and decrementing is the same
whichever operator you use, it's just wrapped in code to return the old/new
value as appropriate.

So right now, for false and true (and for null with --), you can't tell the
difference, because the variable is the same before and after. For null
(with ++), they evaluate to the old or new value, as expected:

$a =3D null; var_dump( $a++, $a ); // NULL, int(1)
$a =3D null; var_dump( ++$a, $a ); // int(1), int(1)


As far as I can see, null and bool are simply missing from the switch
statement that special cases each type of variable:

- increment_function (has null but no bool):
https://github.com/php/php-src/blob/26327bcd3b6375a4883f00a289ba129e5b23717=
d/Zend/zend_operators.c#L2299
- decrement_function (has neither):
https://github.com/php/php-src/blob/26327bcd3b6375a4883f00a289ba129e5b23717=
d/Zend/zend_operators.c#L2359

Regards,
--=20
Rowan Tommins
[IMSoP]

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