Database-less, sessionless way to count online users in PHP.

counter.php

<?php
$timeout = 300; // 5 minutes
$time = time();
$ip = $_SERVER["REMOTE_ADDR"];
$file = "users.txt";
$arr = file($file);
$users = 0;

for ($i = 0; $i < count($arr); $i++){
    if ($time - intval(substr($arr[$i], strpos($arr[$i], "    ") + 4)) > $timeout){
        unset($arr[$i]);
        $arr = array_values($arr);
        file_put_contents($file, implode($arr)); // 'Glue' array elements into string
    }
    $users++;
}

echo $users;

// Only add entry if user isn't already there, otherwise just edit timestamp
for ($i = 0; $i < count($arr); $i++){
    if (substr($arr[$i], 0, strlen($ip)) == $ip){
        $arr[$i] = substr($arr[$i], 0, strlen($ip))."    ".$time."\n";
        $arr = array_values($arr);
        file_put_contents($file, implode($arr)); // 'Glue' array elements into string
        exit;   
    }
}

file_put_contents($file, $ip."    ".$time."\n", FILE_APPEND);
?>

Any Readme /Guide to implement this code to a project?

Hey @zubbey. It's been a while since I've done anything with this, but it should just work with any PHP runtime. All you need is a file called users.txt in the same directory as this script. You probably want to set permissions on users.txt to make sure people can't view it (it stores IP addresses, which could be sensitive).

Then when someone visits counter.php, it will display how many unique IP addresses have also visited it in the last 5 minutes. You can integrate it with an existing website by including it as an iframe.

Thanks, man, it worked just fine.