footer.php

<?php
session_start();
$counter_name = "counter.txt";
// Check if a text file exists. If not create one and initialize it to zero.
if (!file_exists($counter_name)) {
  $f = fopen($counter_name, "w");
  fwrite($f,"0");
  fclose($f);
}
// Read the current value of our counter file
$f = fopen($counter_name,"r");
$counterVal = fread($f, filesize($counter_name));
fclose($f);
// Has visitor been counted in this session?
// If not, increase counter value by one
if(!isset($_SESSION['hasVisited'])){
  $_SESSION['hasVisited']="yes";
  $counterVal++;
  $f = fopen($counter_name, "w");
  fwrite($f, $counterVal);
  fclose($f); 
}
echo 'This system is operated by Anton Janovsky and you can contact me<a href="https://docs.google.com/spreadsheet/viewform?fromEmail=true&amp;formkey=dEZUN2tTUTU1NUdweUxldkcwNmpXNlE6MQ" target="_blank"> here. </a><br>';
echo "You are visitor number ".$counterVal." to this site";
?>