3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php mb_internal_encoding('UTF-8'); echo 'Subject: ', mb_encode_mimeheader('𝕄', 'UTF-8', 'B');
based on WiQHQ
Output for 4.3.0 - 4.3.11, 4.4.2 - 5.0.4, 5.1.0 - 7.2.0
Subject: =?UTF-8?B?8J2VhA==?=
Output for 4.4.0 - 4.4.1, 5.0.5
Subject: D