Is there any other methods other create_XXX_buffer of ctypes to send a string via funcion parameter?

Hi all,
I am trying to make a DLL in D programming language. It has 3 type of strings.
UTF-8 aka string,
UTF-16 aka immutable wchar array for Windows,
UTF-32 aka dstring.
I know there is create_unicode_buffer & create_string_buffer. Other than this, is there any method to send a string to D world via function parameter ?