The WConcatenate method

This method appends a copy of the wide character string from to the end of the wide character string to. If from and to overlap, the results of this method are undefined.

int WConcatenate(ITWChar *to, const ITWChar *from, 
              int nfromwchars = ITLocale::ScanToNul, 
              int ntowchars = ITLocale::ScanToNul) const

If there is an error, this method returns NULL. Call ITLocale::GetError() to retrieve a specific error message.