Knowledge Base

FIX: LDd Suppresses Implicit Definition of _DEBUG

Article ID: 163369

Article Last Modified on 12/10/2003

Microsoft Visual C++ 4.0 Standard Edition
Microsoft Visual C++ 4.1 Subscription
Microsoft Visual C++ 4.2 Enterprise Edition
Microsoft Visual C++ 5.0 Enterprise Edition
Microsoft Visual C++ 6.0 Enterprise Edition
Microsoft Visual C++ 4.2 Professional Edition
Microsoft Visual C++ 5.0 Professional Edition
Microsoft Visual C++ 6.0 Professional Edition
Microsoft Visual C++ 6.0 Standard Edition

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

Keywords: kbbug kbfix kbnoupdate kbcompiler KB163369