3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php mb_internal_encoding('UTF-8'); echo 'Subject: ', mb_encode_mimeheader('€', 'UTF-8', 'B');
based on gN5Nj
Output for 4.3.0 - 7.2.0
Subject: =?UTF-8?B?4oKs?=