Hi I am just learning the PHP object oriented stuff with a book I bought. The book is pretty good but it doesn't explain why the following code doesn't work:

PHP Code:

<?php

class StaticCall
{
    static $_static = -1;
    
    
    public function __construct()
    
    {
        
    //static $_static = -1;
    echo "<p>number is " . $_static;
    
    $_static = 1;
    
    echo "</p><p> and number is " . $_static;
    
    
    }
    
    
}

$static = new StaticCall();

The page is supposed to display the first value of $_static but its blank. like the property is undefined. The second value displays fine as 1. Can someone explain this to me? Or is it my server?

When you reference a member variable of a class in PHP from within that class you need to use the $this reference:

PHP Code:

$this->_static; 


However, static variables and methods should always be referenced from the class definition rather than a particular instance. Using $this will generate this warning: Accessing static property StaticCall::$_static as non static.

When referencing a static variable do it like this:

PHP Code:

StaticCall::$_static 


Also, you shouldn't reassign static variables:

PHP Code:

$this->_static = 1; //don't do this 


Also, within the class that the static member belongs to, you can refer to the variable with the "self" keyword:

PHP Code:

class AnyClass {
     static $_static = 'awesome';
     function __construct() {
         echo self::$_static;//outputs 'awesome'
     }
}