PHP Pass by Reference to Function for Same Object in Class

Question

I am trying to modify an object that has been created by passing it from the class to another function. In my scenario below, I am would expect the result to be 2, but I am getting an "Uncaught Error".

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Index.php
------------------------------
include "class.php";
include "function.php";

$number = new a();

$number->add(1);
echo $number->display();

$number->add_helper();
echo $number->display();

------------------------------
function.php
------------------------------
function get_help(&$numb) {
    $numb->add(1);
}

------------------------------
class.php
------------------------------

class a {

    protected $var;

    public function add($numb) {
        $this->var .= $numb;
    }

    public function display() {
        return $this->var;
    }

    public function add_helper() {
        get_help($this->var);
    }
}

------------------------------

When I run the add_helper function, that is where errors happen. I an expecting the result to be 2.

Thanks in advance for the help.

Will

Answer 1

Thanks to Magnus Eriksson's response...

I was passing the string when I needed to be passing the object.

the add_helper function in my a class should actually be:

    get_help($this);

instead of $this->var.

Thank you Magnus.