php - 当文件中包含数组时，in_array返回false

I'm rebuilding the language system on my php application to make it easier to create translations.

one of the things I did was convert everything to one big array $lang; here is an example of what that looks like:

$lang['common:login'] = "Login";
$lang['common:signup'] = "Sign Up";
$lang['index:title'] = "Home Page";
$lang['messages:newmessages'] = "You have %s new messages";

I load it by using the following code:

require_once "lang/en/lang.php";

calling $lang['common:login'] will wqork with no problem, the problems occurred once I made a function for loading these compared to the other way I've done it in the past.

function outputLanguage($tag) {

    global $lang;

    //see if tag exists.
    if (!in_array($tag, $lang)) {
       return $tag." is an invalid language tag.";
    }  else {
       return $lang[$tag];
    }
}

it seems that in_array() doesn't like to work with arrays that included from another source.

I honestly would like to have some validation in case someone made a mistake, so does anyone know of a good solution?

Thanks.

You need to use array_key_exists instead of in_array

You are looking for the array key, try:

if(!isset($lang[$tag])) {
    return $tag." is an invalid language tag.";
} else {
    return $lang[$tag];
}

Or I would return false:

return isset($lang[$tag]) ? $lang[$tag] : false;