PHP全局变量范围？

Question

update:

the code i put below will be invoked by a form on other webpage. so that's why I didn't made a instance of a obj.

More detail code:

$serverloc='serverURL';

class Aclass{

           function push(){
             global $serverloc;
             echo $serverloc;
             funNotinClass();
           } 

           function otherFunction(){

              echo $serverloc;

           }
}

funNotinClass(){

      echo $serverloc;
}

There is a Class contains 2 functiona "push()" and "otherFunction()" and there is independent function "funNotinClass()" and push() calls it. The class is for a web form in other page. When user click submit the form call the class and use the push() function. A weird thing I found is that the global var $serverloc is invisible to push() and funNotinClass()(they don't print out any thing), but otherFuction() which is a function just like puch() inside of the Aclass can just use the $serverloc(I dont even add global in front of it). How strange....anyone know what is the reason caused this?

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

I read many information about the scope of a global var in php. they all say a global var is defined outside of function or class and you can use it by using global this key word.

So this is my code

$serverloc='serverURL';

class Aclass{

function Afunction(){
 global $serverloc;
 echo $serverloc;

} 
}

but when I run this class it didn't print anything out. Is that because I did something wrong or global var just doesn't work this way. Since all the example I read before are just access a global var in functions directly not a function in a class

Answer 1

As per DaveRandom's comment - you haven't actually made an instance of an Aclass object.

This works and displays data as expected:

<?php 
    $serverloc='serverURL';

    class Aclass{
        global $serverloc;      
        function Afunction()
        {
            echo  $serverloc;
        } 
    }

    $me = new Aclass();

    $me->Afunction(); // output: serverURL

?>

Edit: DaveRandom seems to post asnwers as comments. Go Vote up some of his other answers, the rep belongs to him not me. I am his ghostwriter tonight.

Answer 2

If it is class globals you are after you could do like

class myClass
{    
  private $globVar = "myvariable";

  function myClass()
  {
    return $this->globVar;
  }
}

Answer 3

but when I run this class it didn't print anything out

You don't run classes , in the sense of executing them. A class is a just a data structure that holds data and functions related (called methods).

As most traditional data structures, you create instances of them (called objects), and then you execute actions on them. One way to execute actions on objects (instances of classes), is to pass a message for it to do something: that is calling a method.

So, in your case you could do:

$obj = new Aclass(); // create an object, instance of Aclass
$obj->Afunction();   // ask it to perform an action (call a method)

Having said that, sometimes you want to create a class only for grouping related functions, that never actually really share data within an object. Often they may share data through a global variable (eg.: $_SERVER , $_GET , etc). That may be the case of your design right there.

Such classes can have its methods executed without never instantiating them, like this:

Aclass::Afunction();

While relying on global variables is usually an indicator of quick'n dirty design, there are cases in which it really is the best trade-off. I'd say that a $serverlocation or $baseurl may very well be one of these cases. :)

See more:

• The basics on classes and objects in the PHP manual
• About the static keyword