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Q163369: FIX: LDd Suppresses Implicit Definition of _DEBUG

Article: Q163369
Product(s): Microsoft C Compiler
Version(s): 4.0,4.1,4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbtool kbCompiler kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug kbNoUpdate
Last Modified: 11-FEB-2002

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The information in this article applies to:

- Microsoft Visual C++, versions 4.0, 4.1 
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

When compiler option /LDd follows /MTd, /MDd or /MLd, _DEBUG is not defined.
This happens only if it is compiled from the command line. The IDE adds this
definition by default in the project settings for debug build.

RESOLUTION
==========

Specify /LDd before /MTd, /MDd or /MLd.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

This problem was corrected in Microsoft Visual C++ .NET.

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

When you use one of the compiler options /MTd, /MDd or /MLd, the symbol _DEBUG
is automatically defined. However, if /LDd follows any of these options on the
compiler command line, then _DEBUG is not defined automatically.

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

      // x.cpp or x.c
      // Compile options needed to reproduce: /c /MTd /LDd
      // Compile options for workaround: /c /LDd /MTd
      #ifdef _DEBUG
      #  pragma message("_DEBUG is defined")
      #else
      #  pragma message("_DEBUG is not defined")
      #endif


Additional query words:

======================================================================
Keywords          : kbtool kbCompiler kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug kbNoUpdate 
Technology        : kbVCsearch kbVC400 kbAudDeveloper kbVC410 kbVC420 kbVC500 kbVC600 kbVC32bitSearch kbVC500Search
Version           : :4.0,4.1,4.2,5.0,6.0
Issue type        : kbbug
Solution Type     : kbfix

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