- strstr: documentation ( source)
<?php
echo 'Disponiveis: '. $_SERVER['HTTP_ACCEPT_LANGUAGE'] .'<br>';
$lang = strstr(Locale::acceptFromHttp($_SERVER['HTTP_ACCEPT_LANGUAGE']), '_');
if($lang === 'pt'){
echo 'Olá amigo';
}else if($lang == 'es'){
echo 'Hola amigo';
}else if($lang == 'en'){
echo 'Hello friend';
}