Example of PHP file translated using gettext

I18n_test.php

<?php
  session_start();

  if (isset($_GET["locale"])) {
    $locale = $_GET["locale"];
  }
  else if (isset($_SESSION["locale"])) {
    $locale  = $_SESSION["locale"];
  }
  else {
    $locale = "en_UK";
  }

  putenv("LANG=" . $locale); 
  setlocale(LC_ALL, $locale);


  $domain = "example";
  bindtextdomain($domain, "Locale"); 
  bind_textdomain_codeset($domain, 'UTF-8');

  textdomain($domain);

  $domain2 = "example2";
  bindtextdomain($domain2, "Locale"); 
  bind_textdomain_codeset($domain2, 'UTF-8');

  $user = "Curious gettext tester";

  // _() is an alias of gettext()
  echo _("Let’s make the web multilingual.");
  echo _("We connect developers and translators around the globe 
on Lingohub for a fantastic localization experience.");

  echo sprintf(_('Welcome back, %1$s! Your last visit was on %2$s', $user, date('l'));

  // dgettext() is similar to _(), but it also accepts a domain name if a string from
  // a domain other the one set by textdomain() needs to be displayed
  echo dgettext("example2", "");

  // ngettext() is used when the plural form of the message is dependent on the count
  echo ngettext("%d page read.", "%d pages read.", 1); //outputs a form used for singular
  echo ngettext("%d page read.", "%d pages read.", 15); //outputs a form used when the count is 15
?>

AFAIK it should be "en_GB" instead of "en_UK".