RE: [CONNECT C++] ustnTaskId link error

If you want to use an exported symbol, you will need to add an "import" (IMPORT_ATTRIBUTE) decoration to the function/data member for use within your project.  Typically most public API functions and global/static data members are already pre-decorated for your use within an appropriate header file (.h or .fdf) that you simply include in your project and then proceed to call or use.  BENTLEYDLL_EXPORT may be a better way of thinking that you want "to use an export" vs. IMPORT_ATTRIBUTE that may or may not be as intuitive.  You can modify your sample to work adding the hilighted:

extern "C"
{
#if !defined (mdl)
    BENTLEYDLL_EXPORT extern wchar_t*        ustnTaskId;
#endif
}   //  extern "C"

Or, modify using the macros below which may help improve readability:

BEGIN_EXTERN_C

BENTLEYDLL_EXPORT extern WCharCP      ustnTaskId;

END_EXTERN_C

Headers of interest for these macros are:

Bentley\Bentley.h:64:   #define IMPORT_ATTRIBUTE        __declspec(dllimport)
Bentley\Bentley.h:157: #define BEGIN_EXTERN_C extern "C" {
Bentley\Bentley.h:158: #define END_EXTERN_C              }
Bentley\Bentley.h:242:  #define BENTLEYDLL_EXPORT IMPORT_ATTRIBUTE

HTH,
Bob