How to have a variable accessing through different class methods in PHP?

How is it possible to have a variable inside a class in PHP开发者_如何学Go that is accessible through different methods of the same class? What's the location and syntax of declaration, initialization and accessing?

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Here's a simple example.

<?php
class HelloWorld {
 var $message = '';

 function __construct() {
   $this->message = 'Hello World';
 }

 function say_hi() {
   echo $this->message;
 }
}
?>

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Please read "Classes and Objects: The Basics" in the PHP manual:

http://php.net/manual/en/language.oop5.php

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You can access every variable from your class in all the methods with this :

$this->myVar;

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a variable can be declared inside the class.

<?php
class ExampleClass {
public $pub; // accessable anywhere
protected $pro; // can only be called by this class and classes that extend this class (inherit)
private $pri; // only accessed by this class

}?>

Variable scope is explained here