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Q198130: PRB: FLL Causes Error After Recompilation

Article: Q198130
Product(s): Microsoft C Compiler
Version(s): WINDOWS:3.0,3.0b,5.0,5.0a,6.0; WINNT:6.0
Operating System(s): 
Keyword(s): kbnokeyword kbVC600 kbvfp300 kbvfp500 kbvfp600
Last Modified: 17-JUL-2001

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The information in this article applies to:

- Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a, 6.0 
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SYMPTOMS
========

After building an FLL in Visual C++ 6.0, you may get one of the following error
messages when calling a function in the FLL from Visual FoxPro:

  API Caused an Exception

-or-

  The error occurs when loading the debug build of the FLL, but not with the
  release build.

CAUSE
=====

The project has been compiled in Visual C++ version 6.0 with debug information
using the new "Edit and Continue" format. This is why a release build of the FLL
works and a debug build that uses "Edit and Continue" for the debug information
format fails. The default setting for a debug build in Visual C++ 6.0 is to use
a "Program database for Edit and Continue." This causes tokens to be inserted in
the compiled program that are not recognized by FoxPro.

NOTE: It appears that the errors occur only when compiling on Windows NT.

RESOLUTION
==========

Use one of the following workarounds:

- Compile the project as a release build.

- Change the project settings. In the Project Settings dialog box, click the
  C/C++ tab. Select General in the Category box, and change the selection in
  the Debug Info: box from "Program database for Edit and Continue" to "Program
  Database."

STATUS
======

This behavior is by design.

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

Steps to Reproduce Behavior
---------------------------

1. Locate the HOME()+"Api\Samples" folder.

2. In Visual C++ 6.0, start a new Win32 Dynamic Link Library project named
  Reverse.

3. Add Reverse.C (found in HOME()+"Api\Samples\") to the project.

4. In the Project Settings, make sure the /MDd compiler switch is used. Add
  winapims.lib (found in HOME()+"Api\Samples\") to the Object/library modules
  setting.

5. On the Build menu of Visual Studio, click "Set Active Configuration," and
  select Win32 Debug.

6. Click Rebuild All on the Build menu.

7. SET LIBRARY TO the newly-compiled Reverse.Dll.

8. In the Command window, type "? reverse('test')" (without the double quotation
  marks), and note that one of the two error messages listed above appears.

(c) Microsoft Corporation 1998, All Rights Reserved. Contributions by Mike
Stewart, Microsoft Corporation.


Additional query words:

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Keywords          : kbnokeyword kbVC600 kbvfp300 kbvfp500 kbvfp600 
Technology        : kbVCsearch kbVFPsearch kbAudDeveloper kbVC32bitSearch kbVFP300 kbVFP300b kbVFP500 kbVFP600 kbVFP500a kbVCPE600 kbVCEE600 kbVCLE600
Version           : WINDOWS:3.0,3.0b,5.0,5.0a,6.0; WINNT:6.0
Issue type        : kbprb

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