未定義的屬性？

我剛開始學OOP PHP，我已經做了一些練習，我得到了與返回這些錯誤繼承的類問題：未定義的屬性？

Notice: Undefined property: HtmlEmailer::$recipients in C:\xampp\htdocs\class.htmlemailer.php on line 10 

Warning: Invalid argument supplied for foreach() in C:\xampp\htdocs\class.htmlemailer.php on line 10

爲什麼是未定義的屬性？我的確在emailer.test.php定義它...

我看過3次我的書的同一章，檢查代碼的每一部分，我沒有意識到錯誤所在。

有我的代碼：class.emailer.php

<?php 
/** 
* 
*/ 
class Emailer 
{ 
    private $sender; 
    private $recipients; 
    private $subject; 
    private $body; 

    function __construct($sender) 
    { 
     $this->sender = $sender; 
     $this->recipients = array(); 
    } 

    public function addRecipients($recipients) 
    { 
     array_push($this->recipients, $recipients); 
    } 

    public function setSubject($subject) 
    { 
     $this->subject = $subject; 
    } 

    public function setBody($body) 
    { 
     $this->body = $body; 
    } 

    public function sendEmail() 
    { 
     foreach ($this->recipients as $recipient) 
     { 
      $result = mail($recipient, $this->subject, $this->body, "From: ".$this->sender."\r\n"); 
      if ($result) 
      { 
       echo "Email successfully sent to ".$recipient; 
      } 
     } 
    } 
} 

?>

class.htmlemailer.php

<?php 
/** 
* htmlemailer extends emailer 
*/ 

class HtmlEmailer extends Emailer 
{ 
    public function sendHTMLEmail() 
    { 
     foreach ($this->recipients as $recipient) 
     { 
      $headers = 'MIME-Version: 1.0' . "\r\n"; 
      $headers .= 'Content-type: text/html; charset=utf-8' . "\r\n"; 
      $headers .= 'From: {$this->sender}' . "\r\n"; 

      $result = mail($recipient, $this->subject, $this->body, $headers); 
      if ($result) 
      { 
       echo "HTML mail successfully sent to ".$recipient." ! <br />"; 
      } 
     } 
    } 
} 

?>

emailer.test.php

<html> 

<?php 
/** 
* tests 
*/ 
include_once('class.emailer.php'); 
include_once('class.htmlemailer.php'); 

$emailerobject = new HtmlEmailer('[email protected]'); 
$emailerobject->addRecipients('[email protected]'); 
$emailerobject->setSubject('Some Subject'); 
$emailerobject->setBody('Some body message'); 
$emailerobject->sendHTMLEmail(); 

?> 

</html>

來源

2015-10-21 wdarking

問題就迎刃而解了。感謝rray和mapek。 PS：即時閱讀http://php.net/manual/en/language.oop5.visibility.php現在。 – wdarking

我也遇到過這個問題，谷歌搜索一個解決方案把我帶到這裏，這反過來解決了這個問題（感謝rray，mapek和wdarking），並揭示了另一個小問題：在文件「class.htmlemailer.php」下面的行$ emailerobject-> setbody（'some body mesage'）;你需要添加$ emailerobject-> sendEmail（）;或執行代碼後，您將顯示一個空白的白頁，並且不會發送電子郵件。 – MartinJJ

你不能繼承私人財產只有受保護者或公衆。如果你想要一個下坡類繼承的變化private通過protected，所以他們會acessible。

class Emailer 
{ 
    protected $sender; 
    protected $recipients; 
    protected $subject; 
    protected $body;

來源

2015-10-21 18:36:01 rray

你必須改變

private $recipients;

到

protected $recipients;

使財產在子類中訪問。

請閱讀有關visibility in PHP OOP php的文檔。

來源

2015-10-21 18:38:32

未定義的屬性？

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