PHP函数不会选择变量的值

Question

I have written this as I am learning OOP PHP. I have been having some trouble with passing variables' values to functions. but it turns out that the functions won't read the variables' values. Please see below and advise.

<?php 


 class calculator {

    private $num1 = '1';
    private $num2 = '2';

    public function complete() {

        return $num1 * $num2;

    }

}

$calc = new calculator();
$result = $calc->complete();

echo $result;

Answer 1

You have to change this:

(With $this you access the class property and not any variable)

public function complete() {

    return $num1 * $num2;

}

to this:

public function complete() {

    return $this->num1 * $this->num2;
         //^^^^^ See here^^^^^

}

Answer 2

public function complete() {

    return $num1 * $num2;

}

There is no variable $num1 or $num2 created in this function. Of course it does not "read the variables' values" .

What you want probably is:

public function complete() {

    return $this->num1 * $this->num2;

}

Have you read the chapter about classes and objects in the PHP Manual?