php array access on boolean

I recently stumbled across the following:

<? $d=false; var_dump($d[123]); ?>

which yielded NULL, but (unexpected to me) without any notice, as for example

<? $d=array(开发者_开发技巧); var_dump($d[123]); ?>

does produce the well known

Notice: Uninitialized string offset:  123 in - on line 1

What is going on here? Is there any documentation of this behavior?

From here:

Accessing variables of other types (not including arrays or objects implementing the appropriate interfaces) using [] or {} silently returns NULL.

I guess that is what you would call undefined behaviour.

It makes sense, as a boolean can not have an offset.

error_reporting(E_ALL);
$d = TRUE; 
var_dump($d[0]);

This also produces NULL (if FALSE was coerced to an empty string, it would make sense that TRUE would be 1).

Plus what meze said :)

Quick look at the source code shows that this is expected behavior. But don't ask me why they did it this way...