C#

extern "C" BOOL FindUser(CString csPassword,
                             CString &csUserName,
                             CString &csUserPriveledge,
                             BOOL &bUserActive)
{
   //bunch of code..
    return bFound;
}

; WN_USER_SECURITY.def : Declares the module parameters for the DLL.

LIBRARY      "WN_USER_SECURITY"
DESCRIPTION  'WN_USER_SECURITY Windows Dynamic Link Library'

EXPORTS
		  FindUser @1

namespace Material_OIT
{
    public class RijndaelDLL
    {

        [DllImport("WN_USER_SECURITY.dll")]
        static public extern bool FindUser(StringBuilder password,
                                       ref StringBuilder username,
                                       ref StringBuilder userPriveledge,
                                       ref StringBuilder userID,
                                       ref StringBuilder userComments,
                                       ref bool userActive);


    }
}

RijndaelDLL.FindUser(password1,
                     ref username,
                     ref userPriv,
                     ref userID,
                     ref userCom,
                     ref userActive);