Creating user defined function for firebird 2.5 with c++builder 2010 -

i tried create simple user defined function (udf) firebird 2.5 c++ builder 2010 don't manage work in firebird.

1. creating dll project default setting in c++ builder 2010.

2. adding unit example udf including "ibase.h" , "ib_util.h":

   extern "c" __declspec(dllexport) int __stdcall myfunc ( int )   {        int result = 2 * i;        return result;   }   

3. building dll fbudfmbd.dll in path c:\program files (x86)\firebird\firebird_2_5\udf

4. registering udf via ibexpert in sample db

   declare external function f_myfunc   integer   returns integer  entry_point 'myfunc' module_name 'fbudfmbd'; 

5. calling udf

   select f_myfunc( 3 ) rdb$database; 

   results in error message

   invalid token.   invalid request blr @ offset 36.   function f_myfunc not defined.   module name or entrypoint not found. 

with tool gexperts - pe information can see udf dll-export myfunc ordinal $1 , entry point $1538.

what doing wrong, firebird can't register dll , udf correctly?

is there in dll project change regarding default compiler options?

thanks lot! got help.

top 2: corrected c++-code is:

extern "c" __declspec(dllexport) int myfunc ( int * val ) {    int result = 2 * *val;    return result; } 

pay attention reference call of input parameter.

top 4: register udf in firebird 2.5 db

declare external function f_myfunc integer returns integer value entry_point '_myfunc' module_name 'fbudfmbd'; 

pay attention leading underscore @ function name!

top 5: select f_myfunc( 3 ) rdb$database; works fine!