Integrate visitor counter into website?

I quickly wrote you a “small counter”. Although I didn’t test him, I hope he worked. – Just keep going around and make him fit.

class BesucherZaehler {


    private $datei;


    public function __construct($datei = 'counter.txt') {
        $this->datei = $datei;
    }


    public function zaehleBesucher() {
        $ersterBesuch = !isset($_COOKIE['visited']);
        setcookie('visited', 'yes', time() + 86400); 

        $count = file_exists($this->datei) ? (int)file_get_contents($this->datei) : 0;
        $count = $ersterBesuch ? $count + 1 : $count;
        file_put_contents($this->datei, $count);


        return $count;
    }
}


// Ausgabe 
$zaehler = new BesucherZaehler();
echo "Anzahl der Besucher: " . $zaehler->zaehleBesucher();