$array[] = 1 is not the same as $array[$somenullvalue] = 1. This is not intuitive and undocumented as far as I can tell.

Example:

--8<--

[armadillo:pgl]:~/public_html/test $ cat test.php
<?
#!/usr/local/bin/php -q
$array[] = 1;
$array[] = 2;

print_r($array);

unset($array);

$null = '';

$array[$null] = 3;
$array[$null] = 4;

print_r($array);
?>

--8<--

Prints:

--8<--

Array
(
    [0] => 1
    [1] => 2
)
Array
(
    [] => 4
)

--8<--

I would say this is a documentation problem, but I can't see how this behaviour could be useful.

regards,

Peter Lowe.