ERROR 1127 (HY000): can't find symbol 'add ' in library.

I have been looking for creating a user defined function in MariaDB to perform a simple task

For that I created a sample c++ program for adding two numbers,and compiled using the below command
 g++ -fPIC -shared Hello.cc -o add.so
after that I copied the shared object file to plugin directory.

When Iam calling the Create function syntax 
 
CREATE FUNCTION add RETURNS integer SONAME 'add.so';

it gives the below error
 ERROR 1127 (HY000): Can't find symbol 'add ' in library.

Kindly give a solution for the same.