PHP counts the number of people online on the website

How does php count the number of people online on the website? This article mainly introduces the method of counting the number of people online on a website in PHP. It implements the function of counting the number of people online by obtaining server-side network parameters and reading and writing text files. I hope to be helpful.

The specific implementation method is as follows:

<?php
function getIpAddress() { // 取得当前用户的IP地址
 if (getenv(&#39;HTTP_CLIENT_IP&#39;)) {
 $ip = getenv(&#39;HTTP_CLIENT_IP&#39;);
 } elseif (getenv(&#39;HTTP_X_FORWARDED_FOR&#39;)) {
 $ip = getenv(&#39;HTTP_X_FORWARDED_FOR&#39;);
 } elseif (getenv(&#39;REMOTE_ADDR&#39;)) {
 $ip = getenv(&#39;REMOTE_ADDR&#39;);
 } else {
 $ip = $_SERVER[&#39;REMOE_ADDR&#39;];
 } 
 return $ip;
} 
function writeover($filename,$data,$method = &#39;w&#39;,$chmod = 0){
 $handle = fopen($filename, $method);
 !handle && die("文件打开失败");
 flock($handle, LOCK_EX);
 fwrite($handle, $data);
 flock($handle, LOCK_UN);
 fclose($handle);
 $chmod && @chmod($filename, 0777);
} 
function count_online_num($time, $ip) {
 $fileCount = &#39;./count.txt&#39;;
 $count = 0;
 $gap = 900; //15分钟不刷新页面就
 if (!file_exists($fileCount)) {
 $str = $time . "\t" . $ip . "\r\n";
 writeover($fileCount, $str, &#39;w&#39;, 1);
 $count = 1;
 } else {
 $arr = file($fileCount);
 $flag = 0;
 foreach($arr as $key => $val) {
  $val= trim($val);
  if ($val != "") {
  list($when, $seti) = explode("\t", $val);
  if ($seti ==$ip) {
   $arr[$key] = $time . "\t" . $seti;
   $flag = 1;
  } else {
   $currentTime = time();
   if ($currentTime - $when > 900) {
   unset($arr[$key]);
   }else{
   $arr[$key]=$val;
   }
  } 
  } 
 } 
 if ($flag == 0) {
  array_push($arr, $time . "\t" . $ip);
 } 
 $count = count($arr);
 $str = implode("\r\n", $arr);
 $str.="\r\n";
 writeover($fileCount, $str, &#39;w&#39;, 0);
 unset($arr);
 } 
 return $count;
} 
$time = time();
$ip = getIpAddress();
$online_num = count_online_num($time,$ip);
echo $online_num;
?>

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