11 六章 类 面向对象的PHP

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类中属性： private protected public final static
           final： 防止被子类覆盖

<?php
    //类中常量
    class math_function
    {
        const PI = '3.1415';
        const E = '2.369';
    }
    printf("math_funciton PI is %f.5 ",math_function::PI);
    echo math_function::PI;
    echo "";

    //构造 析构 constructor destructor
    class Book
    {
        private $title;
        private $isbn;
        private $copies;

        //构造
        function __construct($isbn)
        {
            $this->setIsbn($isbn);
            $this->getTitle();
            $this->getNumberCopies();
        }
        //析构
        function __destruct()
        {
            echo " book class instance destroyed.";
        }
        public function setIsbn($isbn)
        {
            $this->isbn = $isbn;
        }
        public function getTitle()
        {
            $this->title = "beginning python";
            print "title:".$this->title."";
        }
        public function getNumberCopies()
        {
            $this->copies = "5";
            print "number copies available: ".$this->copies."";
        }
    }

    $book = new Book("159059519x");


    //子类 调用父类使用
    class book_linux extends Book
    {
        function __construct($isb)
        {
            parent::__construct($isb);
            echo " book_linux  ";
        }
    }
    $linux = new book_linux("19568423");
?>

math_funciton PI is 3.141500.5
3.1415
title:beginning python
number copies available: 5
title:beginning python
number copies available: 5

book_linux

book class instance destroyed.

book class instance destroyed.