爲什麼我需要「＆」？

Question

查看網絡上有關PHP工廠模式的示例。

在行$kind =& Vehicle::category($wheel);，我爲什麼要使用&？

代碼：

<?php 
    class Vehicle { 

     function category($wheel = 0) { 
      if ($wheel == 2) { 
       return "Motor"; 
      } elseif($wheel == 4) { 
       return "Car"; 
      } 
     } 
    } 

    class Spec { 

     var $wheel = ''; 

     function Spec($wheel) { 
      $this->wheel = $wheel; 
     } 

     function name() { 
      $wheel = $this->wheel; 
       return Vehicle::category($wheel); 
     } 

     function brand() { 
      $wheel = $this->wheel; 
       $kind =& Vehicle::category($wheel); 
      if ($kind == "Motor") { 
       return array('Harley','Honda'); 
      } elseif($kind = "Car") { 
       return array('Nisan','Opel'); 
      } 
     } 
    } 

    $kind = new Spec(2); 
    echo "Kind: ".$kind->name(); 
    echo "<br>"; 
    echo "Brand: " . implode(",", $kind->brand()); 
?> 

Answer 1

這是沒用在這裏，因爲例子越來越以一個恆定的參考，但references也有其用途，當你想「看」，可能改變一個值，你希望你的變量隨之改變。

Answer 2

從堆棧溢出 問題Reference - What does this symbol mean in PHP?：

=&參考

• Reference assignment operator in PHP, =&
• What do the "=&" and "&=" operators in PHP mean?
• What do the '&=' and '=&' operators do?
• What does =& mean in PHP?

由於（刪除）評論說，最後一個環節應適用於您的具體情況。