PHP——对象

<?php
/*
 * 创建一个类
 */
class Hello	{
	private $s='Hello world';

	//		function __set($name,$value){
	//			echo '该属性不存在<br/>';
	//		}

	//		function __get($name){
	//			echo '<br/>对象没有属性'.$name;
	//		}

	public function setS($s){
		if ($s!=0){
			$this->s=$s;
		}else{
			$this->s='s变量的值不能为0';
		}
	}

	public function getS(){
		return $this->s;
	}

	public function printHello(){
		echo $this->s;//not $s!!!调用属性不使用$操作符，而采用->操作符
	}
}
$b=new Hello();
$b->printHello();

/*
 * 动态增加对象的属性
 */
//$b->other='test';
//echo '<br/>'.$b->other;

$b->setS(0);
echo '<br/>'.$b->getS();

echo '<br/>';
//print_r(get_defined_constants());

?>

<?php
	/*
	 * define vs const
	 */
	define('PI', '3.14');
	echo constant('PI');
	
	define('AREA', 3.14*100*100);
	echo '<br/>'.constant('AREA');
	
	class MyClass{
		const PI=3.14;//const class scope
		//const AREA=3.14*100*100;// error not support expression
		
		function showPi(){
			echo '<br/>'.self::PI;//use 'self'
		}
	}
	
	$myClass=new MyClass();
	$myClass->showPi();
	echo '<br/>'.MyClass::PI;//out class
?>

<?php
	class Foo{
		private $s;
		private static $ss;//静态属性，又称类属性
		
		function __construct($s){//构造函数
			$this->s=$s;
			self::$ss=$s.$s;
			echo '<br/>s is '.$this->s;
			echo '<br/>ss is '.self::$ss;
		}
		
		function __destruct(){//析构函数
			//close resource
		}
	}
	
	new Foo(1);
?>