這題怎麼做,求解?!!~~~

Question

<?php

/*

一.依照給定選單(menu)和訂單(order)，計算訂單價格總和

*/

$menu = '[

            {"type_id":1,"name":"高菜","food":[

{"food_id":1,"name":"魚香肉絲","price":"10"},

                                            {"food_id":2,"name":"紅燒肉"," price":"11"},

                                                                             ]},

            {"type_id":2,"name":"中菜","food":[

                 _ood        4,"name":"小炒肉","price" :"13"},

                                                                             ]},

            {"type_id":3,"name":"小菜","food":[

                 name":"雪蛋糕","price":"15"} ,

                                                                             ]}      

   

/*

*/

#//num系數量

$order = '[{"food_id":1,"num":2},{"food_id":3,"num":1},{"food_id":6,"num":2}, {"food_id":7,"num":1}]';

#/*

二.設計一個類別Menu，實作以下功能：

1. 設定選單，每個實例必須有且只有一個選單(json字串，結構如上題)

2. 方法calculate, 輸入訂單後(json字串，結構如上題), 輸出格價

3. 方法discount, 可設定折扣，輸出格價時自動計算折扣

4. 靜態方法counter。輸出calculate方法被呼叫的次數

*/

#

Answer 1

class Menu{
private $menu;//選單
private $discountNum=10;//折扣
static $calculateCount=0;//呼叫次數


公共函數__construct($menu){
$this->menu=json_decode($menu,true);
}


公共函數計算($order){
self::$calculateCount++;
$totalPrice=0;
$order=json_decode($order,true);
foreach ($order as $key => $value) {
$foodPrice = $this->getFoodPrice($value['food_id']);
$num=$value['num'];
$totalPrice+=($foodPrice*$num);
}
echo '原總價為:'.$totalPrice.'
';
echo '折扣價為:'.$totalPrice*($this->discountNum/10).'' ;
}


#公用函數discount($discountNum){
return $this->discountNum=$discountNum;
}


public static function counter(){
#echo 'calculate方法的呼叫次數為:'.self::$calculateCount.'
';
#}


public function getFoodPrice($foodId){
foreach ($this->menu as $key => $value) {
foreach ($value['food'] as $key => ; $value) {
if($foodId==$value['food_id']){
return $value['price'];
}
}
}
}


#}


$menu='[
{"type_id":1,"name":"大菜","food":[
{"food_id":1, "name":"魚香肉絲","price":"10"},
{"food_id":2,"name":"紅燒肉","price" :"11"},
{"food_id":3,"name":"香辣粉","price":"12"}
]},
{"type_id":2, "name":"中菜" ,"food":[
{"food_id":4,"name":"小炒肉","price":"13"},
{"food_id": 5,"name":"雲吞食","price":"14"}
]},
{"type_id":3,"name":"小菜","food":[
{"food_id":6, "name":"雪蛋糕","price":"15"},
{"food_id":7,"name":"黃瓜","price":"16" }
]}
]';

##$order1='[
{"food_id":1,"num":2},
{"food_id" :3,"num":1} ,
{"food_id":6,"num":2},
{"food_id":7,"num":1}
]';
$order2='[
{"food_id":1,"num":2},
{"food_id":4,"num":1},
{"food_id":6 ,"num":7},
{"food_id":5,"num":6}
]';
$order3='[
{"food_id":1,"num ":2},
{ "food_id":2,"num":17},
{"food_id":4,"num":24},
{"food_id":7," num":11}
] ';


#$menu1=新選單($menu);
$menu1->折扣(8.7);
$menu1->計算($order1);
$menu1->計算($order2) ;
$menu1->計算($order3);
Menu::counter();

#

Answer 2

把JSON轉成陣列 然後 遍歷循環 陣列 相加就行了

Answer 3

json和陣列轉化，並OOP基礎知識的一併考察，如果覺得無從下手去中文網看看相關影片。