echo "<pre>";
print_r(get_loaded_extensions());
echo "</pre>";
/*
run:
Array
(
[0] => Core
[1] => bcmath
[2] => calendar
[3] => ctype
[4] => date
[5] => ereg
[6] => filter
[7] => ftp
[8] => hash
[9] => iconv
[10] => json
[11] => mcrypt
[12] => SPL
[13] => odbc
[14] => pcre
[15] => Reflection
[16] => session
[17] => standard
[18] => mysqlnd
[19] => tokenizer
[20] => zip
[21] => zlib
[22] => libxml
[23] => dom
[24] => PDO
...
*/