FIX: LDd Suppresses Implicit Definition of _DEBUG (163369)

The information in this article applies to:

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

This article was previously published under Q163369

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

Modification Type:	Major	Last Reviewed:	12/10/2003
Keywords:	kbBug kbCompiler kbfix kbNoUpdate KB163369