<?php
        $fp = @fopen("accessi.txt", 'r');
          if ($fp) {
             $array = explode("\n", fread($fp, filesize("accessi.txt")));
          }
?>
   <span style="font-size:30px; color:red;">Utenti<br>

<?
        echo count($array);
        fclose($file);
?>
</span>