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Re: Help needed with is_null

Posted by Matt Madrid on 08/04/07 04:30

Jerry Stuckle wrote:
> Big Moxy wrote:
>> Would someone be so kind as to tell me what is wrong with this code?
>>
>> (1) This code block indicates the session variable nomex is null.
>> if (is_null($_SESSION['nomex'])){
>> echo " is null.";
>> }
>> else {
>> echo " is not null.";
>> }
>>
>> (2) However on the same page this code block always adds 100 to the
>> price.
>> if ($_SESSION['nomex'] != "^^no^^"){
>
> If it wasn't defined before, it is now.

Maybe, but if referencing an undefined variable sets it, it will be set to NULL.

if ($_SESSION['nothing']){}
var_dump($_SESSION['nothing']);

output: NULL

>
>> if (!is_null($_SESSION['nomex'])){
>
> So this will never be true.

What do you mean it will never be true. It will be true if that variable
had a non-null value to begin with.

>
> BTW - if you're checking to see if something is set, isset() is better.
> But either way, check BEFORE you reference it.
>

Either way in this case.

 

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