How to detect user's timezone?

Question

I need to know what time zone is currently my users are in based on their IP or http header.

I got many answer regarding this issue, but i could not understood thos

Answer 1

Dependencies:

1. http://www.maxmind.com/download/geoip/api/php/php-latest.tar.gz

2. http://geolite.maxmind.com/download/geoip/database/GeoLiteCity.dat.gz

   //Get remote IP
   $ip = $_SERVER['REMOTE_ADDR'];
   
   //Open GeoIP database and query our IP
   $gi = geoip_open("GeoLiteCity.dat", GEOIP_STANDARD);
   $record = geoip_record_by_addr($gi, $ip);
   
   //If we for some reason didnt find data about the IP, default to a preset location.
   if(!isset($record)) {
       $record = new geoiprecord();
       $record->latitude = 59.2;
       $record->longitude = 17.8167;
       $record->country_code = 'SE';
       $record->region = 26;
   }
   
   //Calculate the timezone and local time
   try {
       //Create timezone
       $user_timezone = new DateTimeZone(get_time_zone($record->country_code, ($record->region!='') ? $record->region : 0));
   
       //Create local time
       $user_localtime = new DateTime("now", $user_timezone);
       $user_timezone_offset = $user_localtime->getOffset();        
   }
   //Timezone and/or local time detection failed
   catch(Exception $e) {
       $user_timezone_offset = 7200;
       $user_localtime = new DateTime("now");
   }
   
   echo 'User local time: ' . $user_localtime->format('H:i:s') . '
   ';
   echo 'Timezone GMT offset: ' . $user_timezone_offset . '
   ';
   

citation: SGet visitor local time, sunrise and sunset time by IP with MaxMind GeoIP and PHP by Stanislav Khromov