/*注:
兩種方法即指:
1. abstract class aaa{} (注意aaa中只有抽象方法,沒有一般方法)
class bbb extends aaa{} (在bbb中覆寫aaa中的抽象方法)
2. interface aaa{}
class bbb implements aaa{} (在bbb中覆寫aaa中的抽象方法)
*/
<?php

//abstract root class 抽象根類
abstract class Shape
{
abstract function getArea(); //定義一個(gè)抽象方法
}

//abstract child class 抽象子類
abstract class Polygon extends Shape //多邊形
{
abstract function getNumberOfSides();
}
//concrete class 實(shí)體類 三角形類
class Triangle extends Polygon
{
public $base;
public $height;
public function getArea() //覆寫計(jì)算面積方法
{
return(($this->base * $this->height)/2);
}
public function getNumberOfSides() //覆寫邊數(shù)統(tǒng)計(jì)方法
{
return(3);
}
}
//concrete class 實(shí)體類四邊形
class Rectangle extends Polygon
{
public $width;
public $height;
public function getArea()
{
return($this->width * $this->height);
}
public function getNumberOfSides()
{
return(4);
}
}
//concrete class 實(shí)體類 圓形
class Circle extends Shape
{
public $radius;
public function getArea()
{
return(pi() * $this->radius * $this->radius);
}
}
//concrete root class 定義一個(gè)顏色類
class Color
{
public $name;
}
$myCollection = array(); //建立形狀的集合,放入數(shù)組
//make a rectangle
$r = new Rectangle;
$r->width = 5;
$r->height = 7;
$myCollection[] = $r;
unset($r);
//make a triangle
$t = new Triangle;
$t->base = 4;
$t->height = 5;
$myCollection[] = $t;
unset($t);
//make a circle
$c = new Circle;
$c->radius = 3;
$myCollection[] = $c;
unset($c);
//make a color
$c = new Color;
$c->name = "blue";
$myCollection[] = $c;
unset($c);
foreach($myCollection as $s)
{
if($s instanceof Shape) print("Area: ".$s->getArea()."<br>\n"); //如果$s是Shape類的實(shí)例
if($s instanceof Polygon) print("Sides: ".$s->getNumberOfSides()."<br>\n");
if($s instanceof Color) print("Color:".$s->name."<br>\n");
print("<br>\n");
}
?>