DOCUMENT:Q69898  05-NOV-1999  [win16sdk]
TITLE   :Overcoming "C4071 No Function Prototype Given" Warning
PRODUCT :Microsoft Windows Software Development Kit
PROD/VER:WINDOWS:3.0,3.1
OPER/SYS:
KEYWORDS:kb16bitonly

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The information in this article applies to:

 - Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1 
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SYMPTOMS
========

Code that is compiled using the Microsoft C compiler's warning level 3 (/W3) or
higher and that calls functions through FARPROC pointers causes the Microsoft C
compiler to report warning C4071, "No Function Prototype Given."

CAUSE
=====

Pointers to functions are commonly used when an application explicitly loads
dynamic-link libraries (DLLs) through the Windows LoadLibrary function. Function
pointers declared with FARPROC do not inherit function prototype information.

RESOLUTION
==========

Modify the function pointers declarations to include function prototype
information.

MORE INFORMATION
================

The following code sample uses the generic FARPROC far-pointer-to-function data
type. Compiling the code with Microsoft C at warning level 3 or higher results
in a C4071 warning:

   FARPROC lpfnErrorProc;
   lpfnErrorProc = GetProcAddress(hModule, MAKEINTRESOURCE(1));
   (*lpfnErrorProc)(hWnd, (LPSTR)"Error Message");

However, the following code sample defines custom far-pointer-to- function data
types which provide information about the function arguments. This code does not
produce the warning:

      // typedef declarations
      typedef VOID FAR PASCAL FNERRORPROC(HWND, LPSTR);
      typedef FNERRORPROC FAR *LPFNERRORPROC;

      // variable declaration
      LPFNERRORPROC  lpfnErrorProc;

      // variable assignment and indirect function call
      lpfnErrorProc = GetProcAddress(hModule, MAKEINTRESOURCE(1));
      (*lpfnErrorProc)(hWnd, (LPSTR)"Error Message");

Additional query words: 3.00 3.10

======================================================================
Keywords          : kb16bitonly 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Version           : WINDOWS:3.0,3.1

=============================================================================

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