access modifiers

Let's test the access modifiers we learned earlier.

protected test

protected can also be used in declared classes, and can also be used in inherited child classes.

<?php
    class parents
    {
        protected $parents = "Parental car";
    }

    class child extends parents
    {
        public function rentCar()
        {
            return "Borrow a {$this->parents}";
        }
    }

    $test = new child;
    echo $test->rentCar();
?>

I'll check the results right below.

Result of the code above

The above code declared a property as protected in the parent class. So you could use that property in a child class.
This time, I'll change protected to private in the same code.
Then, of course, it is a property that can only be used in a parent class, so it cannot be used in a child class.

<?php
    class parents
    {
        private $parents = "Parental car";
    }

    class child extends parents
    {
        public function rentCar()
        {
            if(isset($this->parents)){
                return "Borrow a {$this->parents}";
            } else {
                return "I can't rent a car.";
            }
        }
    }

    $test = new child;
    echo $test->rentCar();
?>

I'll check the results right below.

Result of the code above

The isset function determines whether the variable is present and returns true if it exists and false if it does not exist.