Description:
------------
Incrementing null is 1.
Decrementing null is null!

I'm not sure which is the correct behaviour, but they should at least be consistent.


I saw this on PHP 4.4.4 but have since duplicated it on 5.2.3. It was a problem for me because I had a "for ($i = null; $i > 0; $i--)" which results in an infinite loop (but would work fine if $i++ was used instead).


Reproduce code:
---------------
<?php
echo '$i++: ';
$i = null;
var_dump($i);
$i++;
var_dump($i);

echo '<br> <br> <br> $i--: ';
$i = null;
var_dump($i);
$i--;
var_dump($i);

echo '<br> <br> <br> $i - 1: ';
$i = null;
var_dump($i);
$i = $i - 1;
var_dump($i);
?>

Expected result:
----------------
null-- should be 1, so script should output:

$i++: NULL int(1)


$i--: NULL int(-1)


$i - 1: NULL int(-1) 

Actual result:
--------------
null-- is null, script output is:


$i++: NULL int(1)


$i--: NULL NULL


$i - 1: NULL int(-1)