A simple visitor counter

gistfile1.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); 
}

$counterVal = str_pad($counterVal, 5, "0", STR_PAD_LEFT);
$chars = preg_split('//', $counterVal);

$im = imagecreatefrompng("canvas.png");
$src1 = imagecreatefrompng("$chars[1].png");
$src2 = imagecreatefrompng("$chars[2].png");
$src3 = imagecreatefrompng("$chars[3].png");
$src4 = imagecreatefrompng("$chars[4].png");
$src5 = imagecreatefrompng("$chars[5].png");

imagecopymerge($im, $src1, 0, 0, 0, 0, 56, 75, 100);
imagecopymerge($im, $src2, 60, 0, 0, 0, 56, 75, 100);
imagecopymerge($im, $src3, 120, 0, 0, 0, 56, 75, 100);
imagecopymerge($im, $src4, 180, 0, 0, 0, 56, 75, 100);
imagecopymerge($im, $src5, 240, 0, 0, 0, 56, 75, 100);

// Output and free from memory
header('Content-Type: image/png');
echo imagepng($im);
imagedestroy($im);
?>