Functions that I use to localize my apps

gistfile1.php

<?php

function i18n($file = null) {
  global $transtation;
	
	$transtation = array();
	
	if (!isset($_SESSION['lang'])) $_SESSION['lang'] = 'en';
	if (!$file) $file = 'default';
	
	$file = dirname(__FILE__) . "/locale/{$_SESSION['lang']}/{$file}.po";
	
	if (!file_exists($file)) return;
	
	$po = file($file);
	
	foreach ($po as $line):
		if (substr($line, 0, 5) == 'msgid') {
			$current = trim(substr(trim(substr($line, 5)), 1, -1));
		}
		
		if (substr($line, 0, 6) == 'msgstr') {
			$transtation[$current] = trim(substr(trim(substr($line, 6)), 1, -1));
		}
	endforeach;
}

function __($msgid) {
	global $transtation;
	
	if (!isset($transtation[$msgid]) || $transtation[$msgid] == '') {
		return $msgid;
	} else {
		return $transtation[$msgid];
	}
}

// Just some random function to get the current key of the key/value from the PO file

function __KEY($key_or_value) {
	global $transtation;
	
	foreach ($transtation as $key=>$value):
		if ($key == $key_or_value || $value == $key_or_value) return $key;
	endforeach;
	
	return false;
}