Question

How to pass a $_GET variable into function?

$_GET['TEST']='some word';
public function example() {       
   //pass $_GET['TEST'] into here
}

When I try to access $_GET['TEST'] in my function, it is empty.

Answer 1

The $_GET array is one of PHPs superglobals so you can use it as-is within the function:

public function example() {       
   print $_GET['TEST'];
}

In general, you pass a variable (argument) like so:

public function example($arg1) {       
   print $arg1;
}
example($myNonGlobalVar);