PHP类继承初学者 [英] PHP Class Inheritance for Beginners

问题描述

class User{
    public $company_name;
}

class Employer extends User{
    public $fname;
    public $sname;
}

这是我创建的test.php。我已包含类文件。

this is the test.php i have created. I have included the class file.

$employer = new Employer();
$user = new User();
$employer->company_name = "Company name is ";
echo $user->company_name;

当我打印名字没有发生任何事情，请让我知道我的代码是什么。 / p>

When i print the name nothing happens, please let me know what is the wrong with my code.

推荐答案

您的 Employer 类扩展了 / code>类，但是当您创建 $ user 和 $ employer 对象时，它们是单独的实体， 。

Your Employer class extends your User class but when you create your $user and $employer objects they are separate entities and unrelated.

想象你的对象：

$employer = new Employer();
// You now have $employer object with the following properties:
// $employer->company_name;
// $employer->fname;
// $employer->sname;

$user = new User();
// You now have $user object with the following properties:
// $user->company_name;

$employer->company_name = "Company name is ";
// You now have $employer object with the following properties:
// $employer->company_name = 'Company name is ';
// $employer->fname;
// $employer->sname;

echo $user->company_name;
// You currently have $user object with the following properties:
// $user->company_name;  /* no value to echo! */

如果要使用继承的属性，它的工作原理更类似：

If you want to use inherited properties, it works more like this:

class User{
    public $company_name;

    function PrintCompanyName(){
        echo 'My company name is ' . $this->company_name;
    }
}

class Employer extends User{
    public $fname;
    public $sname;
}

$employer = new Employer();
$employer->company_name = 'Rasta Pasta';
$employer->PrintCompanyName();  //echoes 'My company name is Rasta Pasta.'

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