Zend API: Wrapping C++ Classes in a PHP Extension
http://devzone.zend.com/1435/wrapping-c-classes-in-a-php-extension/
Zend API: Hacking the Core of PHP
http://php.net/manual/en/internals2.ze1.zendapi.php
PHP-CPP
http://www.php-cpp.com/
similar - https://www.pipiscrew.com/2016/01/php-call-dotnet-method/