PHP致命错误：无法访问空属性[重复]

Question

This question already has an answer here:

• What is the syntax for accessing PHP object properties? [closed] 3 answers

I am keep getting this error when I wrote my Email class in php.

class Email {

public $mail;

function __construct() {
    $this->$mail = new PHPMailer(true);
    $this->$mail->SMTPDebug=1;

    $this->$mail->isSMTP();

    $this->$mail->SMTPAuth = true;

    $this->$mail->Host = '************'

    $this->$mail->SMTPSecure = 'ssl';

    $this->$mail->Port = 465;

    $this->$mail->Hostname = '************';

    $this->$mail->CharSet = 'UTF-8';

    $this->$mail->FromName = '*************';

    $this->$mail->Username = '*************';

    $this->$mail->Password = '**************';

    $this->$mail->From ='***********';
}

When I new a Email Class, it said cannot access empty property at

$this->$mail = new PHPMailer(true);

I have tried to do this

public $mail = new PHPMailer();

it said it is a syntax error.

Can someone help?

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Answer 1

Problem:

String prefixed with $ character are being interpreted as variables and this includes accessing class properties through a variable:

Example:

$property = 'address';
echo $this->$property;

$property is being resolved to address, therefore $this->$property evaluates to $this->address.

In your case $mail had no value assigned to it, therefore when accessing $this->$mail you were accessing empty property $this-> and trying to assign:

$this-> = new PHPMailer();

Solution:

Omit the $ character when accessing class properties directly.

class Email {

public $mail;

function __construct() {
    $this->mail = new PHPMailer(true);
    $this->mail->SMTPDebug=1;

    $this->mail->isSMTP();

    $this->mail->SMTPAuth = true;

    $this->mail->Host = '************'

    $this->mail->SMTPSecure = 'ssl';

    $this->mail->Port = 465;

    $this->mail->Hostname = '************';

    $this->mail->CharSet = 'UTF-8';

    $this->mail->FromName = '*************';

    $this->mail->Username = '*************';

    $this->mail->Password = '**************';

    $this->mail->From ='***********';
}