Demo6.php
<?php
header ( 'Content-Type:text/html; charset=utf-8;' );
class Computer {
private $_name;
private $_model;
private $_cpu;
//__set 和 __get 方法私有了，还是可以执行，是因为
//因为目前程序的指针已经在类内了。而类内可以执行封装的方法
//类内执行私有方法，不会出现任何错误。
//它只需要间接的拦截就可以了。拦截是在内类执行的。
//说白了，__set() 和 __get() 是 PHP 内置的方法，具有一定的特殊性
private function __set($_key, $_value) {
$this->$_key = $_value;
}
private function __get($_key) {
return $this->$_key;
}
}
$computer = new Computer ();
$computer->_name = '联想';
$computer->_cpu = '四核';
$computer->_model = 'i7';
echo $computer->_name;
echo $computer->_cpu;
echo $computer->_model;
?>
Demo7.php
<?php
header ( 'Content-Type:text/html; charset=utf-8;' );
class Computer {
const NAME = 'DELL';
}
//常量的输出方法 类::常量
echo Computer::NAME; //DELL
?>
Demo8.php
<?php
header ( 'Content-Type:text/html; charset=utf-8;' );
class Computer {
public $_count = 0;
public function _add(){
$this -> _count++; //$_count = $_count+1 $_count++
}
}
//做一个累计的效果
$computer1 = new Computer();
$computer1 ->_add();
$computer1 ->_add();
$computer1 ->_add();
echo $computer1 -> _count;
echo '<br />';
$computer2 = new Computer();
$computer2 ->_add();
$computer2 ->_add();
$computer2 ->_add();
echo $computer2 -> _count;
?>
Demo9.php
<?php
header ( 'Content-Type:text/html; charset=utf-8;' );
class Computer {
public static $_count = 0;
public function _add(){
//如果是静态成员字段，那么就应该用 self 来调用，而不是 $this
self::$_count++;
}
}
//做一个累计的效果
$computer1 = new Computer();
$computer1 ->_add();
echo Computer::$_count;
$computer1 ->_add();
echo Computer::$_count;
$computer1 ->_add();
echo Computer::$_count;
echo '<br />';
$computer2 = new Computer();
$computer2 ->_add();
echo Computer::$_count;
$computer2 ->_add();
echo Computer::$_count;
$computer2 ->_add();
echo Computer::$_count;
?>
Demo10.php
<?php
header ( 'Content-Type:text/html; charset=utf-8;' );
class Computer {
public static $_count = 0;
public static function _add(){
self::$_count++;
}
}
Computer::_add();
Computer::_add();
Computer::_add();
echo Computer::$_count;
?>
Demo11.php
<?php
header ( 'Content-Type:text/html; charset=utf-8;' );
class Computer {
}
$computer = new Computer();
echo $computer instanceof Computer;
?>
