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PHP Fatal error: Cannot access empty property

Asked 1 Year ago Answers: 5 Viewed 10 times

I'm new to php and I have executed below code.

<?php
class my_class{

    var $my_value = array();
    function my_class ($value){
        $this->my_value[] = $value;
    }
    function set_value ($value){
    // Error occurred from here as Undefined variable: my_value
        $this->$my_value = $value;

    }

}

$a = new my_class ('a');
$a->my_value[] = 'b';
$a->set_value ('c');
$a->my_class('d');

foreach ($a->my_value as &$value) {
    echo $value;
}

?>

I got below errors. What could be the error?

Notice: Undefined variable: my_value in C:xampphtdocsMyTestPagesf.php on line 15

Fatal error: Cannot access empty property in C:xampphtdocsMyTestPagesf.php on line 15

Answers

You access the property in the wrong way. With the $this->$my_value = .. syntax, you set the property with the name of the value in $my_value. What you want is $this->my_value = ..

$var = "my_value";
$this->$var = "test";

is the same as

$this->my_value = "test";

To fix a few things from your example, the code below is a better aproach

class my_class {

    public  $my_value = array();

    function __construct ($value) {
        $this->my_value[] = $value;
    }

    function set_value ($value) {
        if (!is_array($value)) {
            throw new Exception("Illegal argument");
        }

        $this->my_value = $value;
    }

    function add_value($value) {
        $this->my_value = $value;
    }
}

$a = new my_class ('a');
$a->my_value[] = 'b';
$a->add_value('c');
$a->set_value(array('d'));

This ensures, that my_value won't change it's type to string or something else when you call set_value. But you can still set the value of my_value direct, because it's public. The final step is, to make my_value private and only access my_value over getter/setter methods

Wednesday, June 9, 2021

muaaz

The PHPUnit documentation ~~says~~ used to say to include/require PHPUnit/Framework.php, as follows:

require_once ('PHPUnit/Framework/TestCase.php');

UPDATE

As of PHPUnit 3.5, there is a built-in autoloader class that will handle this for you:

require_once 'PHPUnit/Autoload.php';

Thanks to Phoenix for pointing this out!

Thursday, April 1, 2021

innovation

The answer was due to hidden characters located in the lessons.db file.

The error shown had nothing to do with this and I would like to thank everyone who took the time to give their two pence.

Thursday, April 1, 2021

FWH

You are trying to pass a pointer to your array in array_push. That is why the fatal error is encountered. Simply use:

array_push( $image_set, $images[fname] );

Note: array_push() will raise a warning if the first argument is not an array.

Saturday, August 14, 2021

Zulakis

You appear to have an error on line 21. Change:

$this->$password

to:

$this->password

For reference, this is is known as a variable variable. Example:

$a = 'b';
$b = 'I am a variable variable';
echo $$a; // equivalent to `echo $b;` prints 'I am a variable variable'

Monday, October 11, 2021

Tom Lilletveit

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PHP Fatal error: Cannot access empty property

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