Set static value throughout site

Was easy in ASP, please help me in PHP!

[bateman_ap]

I have come across a bit of a problem in PHP, my background was classic ASP and have decided to learn a bit of PHP as .net just confuses me too much!

What I am trying to do is set a "API Key" that is used throughout the site. I have a "functions.php" file that is included on every page that I thought I could just set the key in, however it doesn't seem to work. At the moment I have:

$apikey= '123456789';

at the top of my functions.php, I am then trying to use it in a function as shown below:

function writeWidget($widgetid)
$param = array(
 'apikey' => $apikey,
 'widgetid' => $widgetid
);
.....

However when I run it I get:

Notice: Undefined variable: apikey

If I hardcode it in the functino it works perfectly, any ideas, I must be being stupid!

[tomda]

The variable $apikey is not defined...

Just call it as a global variable within the function

function writeWidget($widgetid) {
global $apikey;
$param = array(
'apikey' => $apikey, 
'widgetid' => $widgetid 
); 
.....}

[bateman_ap]

Many thanks, worked perfectly. Out of interest why do you have to define it in every funciton?

[tomda]

PHP.net says

In PHP global variables must be declared global inside a function if they are going to be used in that function.

[php.net...]

[penders]

If you don't declare it global in the function, then another variable (of the same name) will be created local to that function.

Alternatively you could refer to the $GLOBALS[] array in order to access your global variable. This is a superglobal and can therefore be accessed directly in any scope.

function writeWidget($widgetid) { 
 $param = array(  
  'apikey' => $GLOBALS['apikey'],  
  'widgetid' => $widgetid  
 ); 
}

Or, you could define() a constant (if apikey is constant?) instead of using a global variable. Constants can also be accessed in any scope (but cannot obviously be changed)...

define('APIKEY','123456789'); 
function writeWidget($widgetid) { 
 $param = array(  
  'apikey' => APIKEY,  
  'widgetid' => $widgetid  
 ); 
}

"By convention, constant identifiers are always uppercase." (Constants - PHP Manual [uk.php.net])