global vs. static in PHP4?

-_-PHP-_-

Hi all,

I just wanted to find out that is there a really difference between the global variable and the static variable that are only initialized once through out the php file?

i.e.

<?phg

$a = 0;
static $b = 0;
..
..
..

?>

I'm using the Zend Studio and the debugger does not warn static declaration in the page (not in the function) as an error, so I suppose static can be declared anywhere besides within the function; but then, if the variable is initialized only once throughout the page then does it really matter to declare as static?

Does httpd process keep static variables in the memory even after the script execution? or it initializes all variables every time script is executed??

-_-PHP-_-

It seems like a httpd process does not hold the static variable in the memory even after the execution or multiple httpd processes do not share the same static variable allocated in the memory. So to me, it does not make any difference between the global and the static variables that are initialized only once throughout the file.

<?

class Singlton
{
    function Singlton()
    {
    }

function getInstance()
{
    // static variable only accessable by this method
    static $onlyInstance;

    if(!isset($onlyInstance))
    {
            $onlyInstance = new Singlton();
    }

    return $onlyInstance;
}
}

?>

<?

// global variable accessable from anywhere
$_SINGLTON_INSTANCE;

class Singlton
{
    function Singlton()
    {
    }

function getInstance()
{
    global $_SINGLTON_INSTANCE;

    if(!isset($_SINGLTON_INSTANCE))
    {
            $_SINGLTON_INSTANCE = new Singlton();
    }

    return $_SINGLTON_INSTANCE;
}
}

?>

The above examples are pretty much the same to me except that the $onlyInstance is only accessable by invoking the Singlton::getInstance() while $_SINGLTON_INSTANCE can be accessed anywhere. So I guess it's just up to the programmers how it should be designed (the scope issues).

Please let me know if you know more about Zend Engine for PHP 4 about this.