INFO: _DEBUG Must Be Defined When Linking to Debug Libraries

• The Microsoft Foundation Classes (MFC) included with:

      - Microsoft C/C++ version 7.0
      - Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, 1.52
      - Microsoft Visual C++, 32-bit Edition, version 1.0
  

SUMMARY

To link an application with the debugging version of the Microsoft Foundation Class (MFC) libraries, the source code must define the _DEBUG macro at compile time. Specify the name of the appropriate MFC library on the LINK command line before the name of the appropriate C/C++ Run-time Library.

MORE INFORMATION

The debugging versions of the MFC libraries provide additional debugging information in functions that the C/C++ run-time libraries normally provide (such as "new" and "delete"). An attempt to link code compiled when the_DEBUG macro is not defined with the debugging libraries may fail and LINK may generate errors similar to the following:

   C:\...\MFC\lib\safxcwd.lib(memory.cpp) : error L2025: public:
      static void __near* __near __cdecl
      CObject::operator new(unsigned int) : symbol defined
      more than once

   C:\...\MFC\lib\safxcwd.lib(memory.cpp) : error L2025: public:
      static void __near __cdecl
      CObject::operator delete(void __near*) : symbol defined
      more than once

   cl /AS /D_DEBUG test.cpp safxcwd.lib

   cl /D_DEBUG /D_X86_ test.cpp nafxcwd

When you compile code that uses the Microsoft Foundation Classes in Visual Workbench (VWB) in Visual C++ 1.0 or 1.5 for Windows, or Visual C++, 32-bit edition, version 1.0, select the Use MFC Libraries option. (To do so, choose Project from the Options menu, then select Use Microsoft Foundation Classes and choose OK.) VWB automatically inserts the /D_DEBUG option when is compiles the debugging version of your application. The VWB- generated LINK command specifies the appropriate Microsoft Foundation Classes library and the appropriate C/C++ run-time library in the correct order.

In Visual C++, 32-bit Edition, version 2.0 and later, internal makefiles automatically include a /D_DEBUG option on the build line debug targets. Therefore, removing /D_DEBUG from the preprocessor command line options does not cause an error.

Keywords          : MfcMisc kbfasttip kbinfo
Technology        : kbmfc
Version           : 1.0 1.5 1.51 1.52 7.0
Platform          : MS-DOS NT WINDOWS