将PHP代码片段插入自定义wordpress主题的理想位置是什么，因此可以广泛访问全局变量？

Question

I'm playing around with a custom theme for Wordpress and I have this code snippet in my header, home and footer.php files.

<?php

//Get the Wordpress page_id and language for use in template items.

global $pg_id;
global $lang;

if ($_GET["page_id"] && is_numeric($_GET["page_id"])) {
    $pg_id = $_GET["page_id"];
}

$validLang = array("en", "fr");

if ($_GET["lang"] && in_array($_GET["lang"], $validLang)) {
    $lang = $_GET["lang"];
} else {
    $lang = "en";
}

//echo ($lang);
//echo ($pg_id);

?>

I should have this code in one location. Where should I place it so the global variable $lang is available in the header, footer, home and other template files?

Answer 1

I couldn't get the function working properly in functions.php (although I do think that's a possible location to place the code). I ended up using a php include: http://php.net/manual/en/function.include.php