PRODUCT  :  C++                                    NUMBER  :  866
  VERSION  :  All
       OS  :  WIN
     DATE  :  October 19, 1993                         PAGE  :  1/1

    TITLE  :  Using The Windows API Function MakeProcInstance




  I keep getting a type mismatch error from the compiler when I
  pass my function pointer to MakeProcInstance, and a type mismatch
  error when I assign my function's return value to another
  function pointer.  Why?

  Unless two functions take the same parameters, they are
  considered to be of different types.  Thus, if I declare a
  DlgProc like so:

       int FAR PASCAL _export DlgProc(HWND, WORD, WORD, DWORD);

  I will get a type mismatch when I do:

       MakeProcInstance(DlgProc, hInstance);

  because MakeProcInstance expects a FARPROC for its first
  parameter, which is declared to be a

       typedef int (FAR PASCAL *FARPROC)();

  To suppress this error, do this:

       MakeProcInstance((FARPROC)DlgProc, hInstance);

  That is typecast the function pointer you're passing to
  MakeProcInstance to be the type it expects.  Similarly, since
  MakeProcInstance returns a FARPROC, you will get an error if you
  assign its return value into other than a FARPROC.  You would
  need to either make the variable your assigning
  MakeProcInstance's return value into a FARPROC, or typecast the
  return value to the type of your variable.

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