undefined variable

[Tim Streater]

$str = "fcc: " . $PTR_fcc;
Now, upon examination it appears that I have an instance where $str ends up
fcc: undefined
My question is, under what conditions can a variable be set by the PHP system
to the string "undefined"? Would this require that my ajax call in the
... &PTR_fcc=undefined 


Not explicit as such, but that is what’s happening. Javascript will use the
string "undefined" whenever an undefined variable is concatenated on to a
string.

How about if PTR_fcc is not so much undefined on the JavaScript side, as an empty string. So that I'm passing e.g. this, via AJAX:

... &PTR_fcc=&myvar=27 ...

What does that mean in my PHP script when I then do:

$PTR_fcc = isset($_POST['PTR_fcc'])==true ? $_POST['PTR_fcc'] : 0;

i.e. what value does $_POST['PTR_fcc'] have?

[Aziz Saleh]

$str = "fcc: " . $PTR_fcc;
Now, upon examination it appears that I have an instance where $str

ends up

fcc: undefined
My question is, under what conditions can a variable be set by the PHP

system

to the string "undefined"? Would this require that my ajax call in the
... &PTR_fcc=undefined 


Not explicit as such, but that is what’s happening. Javascript will use

the

string "undefined" whenever an undefined variable is concatenated on to a
string.

How about if PTR_fcc is not so much undefined on the JavaScript side, as
... &PTR_fcc=&myvar=27 ...
$PTR_fcc = isset($_POST['PTR_fcc'])==true ? $_POST['PTR_fcc'] : 0;
i.e. what value does $_POST['PTR_fcc'] have?
--
Cheers -- Tim
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A variable is undefined if it was never initialized. In your question, the
value of $PTR_fcc would be empty "" because $_POST['PTR_fcc'] was
initialized to an empty string.

To validate for empty strings as well:

$PTR_fcc = !empty($_POST['PTR_fcc']) ? $_POST['PTR_fcc'] : 0;

Aziz

[Jim Lucas]

Post by Tim Streater

$str = "fcc: " . $PTR_fcc;
Now, upon examination it appears that I have an instance where $str ends up
fcc: undefined
My question is, under what conditions can a variable be set by the PHP system
to the string "undefined"? Would this require that my ajax call in the
... &PTR_fcc=undefined …

Not explicit as such, but that is what’s happening. Javascript will use the
string "undefined" whenever an undefined variable is concatenated on to a
string.

... &PTR_fcc=&myvar=27 ...
$PTR_fcc = isset($_POST['PTR_fcc'])==true ? $_POST['PTR_fcc'] : 0;
i.e. what value does $_POST['PTR_fcc'] have?

http://www.php.net/manual/en/function.var-dump.php is your new best friend!

Post by Tim Streater
--
Cheers -- Tim