Question

所以我有这段代码：

<?php
class Product
{
    public $name = 'default_name';
    public $price = 0;
    public $desc = 'default description';

    function __construct($name, $price, $desc){
        $this->name = $name;
        $this->price = $price;
        $this->desc = $desc;
    }

    public function getInfo(){
        return "Product Name: " . $this->name;
    }
}
$p = new Product();
$shirt = new Product("Space Juice T-Shirt", 20, "Awesome Grey T-Shirt");
$soda = new Product("Space Juice Soda", 2, "Grape Flavored Thirst Mutilator");

echo $shirt->getInfo();
?>

和PHP报告“缺少Product :: __ construct（）的参数1”错误。我在一个领先的PHP课程中得到了这个例子，我很困惑，因为在这个简单的代码中似乎有一个错误。帮助会非常有用。

Answer 1

在您的代码中，如果您要创建Product实例，则必须传递参数。而您已经拥有默认值。所以，确保安全：

<?php
class Product
{
    public $name = 'default_name';
    public $price = 0;
    public $desc = 'default description';

    function __construct($name = null, $price = null, $desc = null){
        $this->name = $name ?: $this->name;
        $this->price = $price ?: $this->price;
        $this->desc = $desc ?: $this->desc;
    }

    public function getInfo(){
        return "Product Name: " . $this->name;
    }
}
$p = new Product();
$shirt = new Product("Space Juice T-Shirt", 20, "Awesome Grey T-Shirt");
$soda = new Product("Space Juice Soda", 2, "Grape Flavored Thirst Mutilator");

echo $shirt->getInfo();
?>

Answer 2

您的构造不允许变量为空，因此

$p = new Product();

造成了这个问题。对于$ name，$ price和$ desc，它期待一些价值，即使它只是空字符串。

如果您将构造函数更改为：

function __construct($name = 'default_name', $price = 0, $desc = 'default description'){
    $this->name = $name;
    $this->price = $price;
    $this->desc = $desc;
}

那么它不应再抛出那个错误了。

缺少Product :: __ construct（）的参数1

2 个答案: