Posted by J.O. Aho on 01/09/07 13:07

Paul Lautman wrote:
> I have the following switch statement:
>
> switch ($record->sub_page) {
> case -1:
> $this->page = 6;
> $error_message = '<center>You appear to have already completed the
> form.</center>';
> break;
> case 0:
> $this->page = 5;
> ff_query("UPDATE #__gateway_form_1 SET `sub_page`=-1 WHERE
> userid=$my->id and `expiry_date` = '$expiry_date'");
> break;
> default:
> do something else
> }
>
> The value of $record->sub_page can be NULL. If it is NULL, the case for 0
> seems to fire. I really need the default action to happen when
> $record->sub_page is NULL or a +ve value.
>
> However if I do:
>
> switch ($record->sub_page) {
> case -1:
> $this->page = 6;
> break;
> case NULL:
> do something else;
> break;
> case 0:
> $this->page = 5;
> break;
> default:
> do something else;
> }
>
> then the switch manages to tell the difference between a NULL and a zero.
>
> Is it correct that php treats NULL as 0?
> Can anyone suggest a good fix?

NULL and 0 are many times treated as false, so you do need to take care of
things and check NULL/0/false.

--

//Aho

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