Private Property

A private property can only be changed from inside the class.

private_property.php

<?php
class ScoreBox
{
    private int $score = 0;

    public function add(int $points): int
    {
        $this->score = $this->score + $points;
        return $this->score;
    }
}

$points = ;
$box = new ScoreBox();
$total = $box->add($points);

echo "points=" . $points . "\n";
echo "total=" . $total . "\n";

<?php
class ScoreBox
{
    private int $score = 0;

    public function add(int $points): int
    {
        $this->score = $this->score + $points;
        return $this->score;
    }
}

$points = ;
$box = new ScoreBox();
$total = $box->add($points);

echo "points=" . $points . "\n";
echo "total=" . $total . "\n";

<?php
class ScoreBox
{
    private int $score = 0;

    public function add(int $points): int
    {
        $this->score = $this->score + $points;
        return $this->score;
    }
}

$points = ;
$box = new ScoreBox();
$total = $box->add($points);

echo "points=" . $points . "\n";
echo "total=" . $total . "\n";

hidden state Private state lets the class control how a value changes.