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Q123493: OutputDebugString() Without \n May GP Fault in MSVC.EXE

Article: Q123493
Product(s): Microsoft C Compiler
Version(s): 1.5,2.0
Operating System(s): 
Keyword(s): kbfile kbpatch kbDebug kbide
Last Modified: 11-FEB-2002

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The information in this article applies to:

- The Integrated Debugger, used with:
   - Microsoft Visual C++ for Windows, 16-bit edition, version 1.5 
   - Microsoft Visual C++, 32-bit Editions, version 2.0 
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SUMMARY
=======

If character strings passed as arguments to the OutputDebugString() API do not
end with a newline character \n, corrupt output appears in the Integrated
Debugger's Output Window. In addition, a general protection fault (GP) fault can
occur in MSVC.EXE. The Microsoft Foundation Classes (MFC) TRACE() macro and
CDumpContext class both use the OutputDebugString() API to send information to
the Integrated Debugger's Output window. Therefore, using a character string
without a newline character with the MFC TRACE() macro or CDumpContext class,
will also cause this problem. Avoid passing strings that do not have an appended
newline character to OutputDebugString(), TRACE(), and CDumpContext objects.
Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This problem was not reproducible in Microsoft Visual
C++, 32-bit Edition, version 4.0.

NOTE: Microsoft has released a patch to Visual C++ version 1.5 that will fix this
problem. This patch will modify the Visual Workbench 1.50, the new one will be
version 1.50.01.

The following files are available for download from the Microsoft Download
Center:

VC1501.exe

For additional information about how to download Microsoft Support files, click
the article number below to view the article in the Microsoft Knowledge Base:

  Q119591 How to Obtain Microsoft Support Files from Online Services

Microsoft used the most current virus detection software available on the date of
posting to scan this file for viruses. Once posted, the file is housed on secure
servers that prevent any unauthorized changes to the file.


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

Steps to Reproduce Problem
--------------------------

1. Add the following code to an executable portion of your application:

        int i;
        for (i=0; i<500; i++)
           OutputDebugString( "This is a test!!!" );

2. Rebuild the application, and run it (press the F5 key) such that the Debug
  Output window is hidden.

3. While the loop of code is executing, switch to the Debug Output window, and
  scroll through the text. Or attempt to select a portion of the text using the
  mouse. You'll see garbage in the Output Window. Prolonged scrolling will
  occasionally generate a GP fault in MSVC.EXE.

Additional query words: GPF

======================================================================
Keywords          : kbfile kbpatch kbDebug kbide 
Technology        : kbVCsearch kbAudDeveloper kbIntegratedDebugger
Version           : :1.5,2.0
Solution Type     : kbfix

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