enabling-debug-features-in-visual-cpp-d-debug.md

title	description	ms.date	ms.topic	dev_langs	helpviewer_keywords	author	ms.author	manager	ms.subservice
Enabling Debug Features in C++ projects (-D_DEBUG)	In Visual C++ you enable debugging features by defining _DEBUG. Learn how to do this, and learn how to link an MFC program in order to debug it.	11/04/2016	conceptual	CSharp VB FSharp C++	/D_DEBUG compiler option [C++] debugging [C++], enabling debug features debugging [MFC], enabling debug features assertions, enabling debug features D_DEBUG compiler option MFC libraries, debug version debug builds, MFC _DEBUG macro	mikejo5000	mikejo	mijacobs	debug-diagnostics

Enabling Debug Features in C++ projects (/D_DEBUG)

In Visual C++, debugging features such as assertions are enabled when you compile your program with the symbol _DEBUG defined. You can define _DEBUG in one of two ways:

• Specify #define _DEBUG in your source code, or

• Specify the /D_DEBUG compiler option. (If you create your project in Visual Studio using wizards, /D_DEBUG is defined automatically in the Debug configuration.)

  When _DEBUG is defined, the compiler compiles sections of code surrounded by #ifdef _DEBUG and #endif.

  The Debug configuration of an MFC program must link with a Debug version of the MFC library. The MFC header files determine the correct version of the MFC library to link with based on the symbols you have defined, such as _DEBUG and _UNICODE. For details, see MFC Library Versions.

Related content

• Debugging Native Code
• Project Settings for a C++ Debug Configuration