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Thank you very much. Yes, this problem appeared after an upgrade today. I just renamed MemDC of my own, and the trouble is gone.
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Thank you very much. Yes, this problem appeared after an upgrade today. I just renamed MemDC of my own, and the trouble is gone.

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Dear experts,<br />
<br />
My application worked fine, but suddenly started giving me <br />
<br />
5&gt;nafxcw.lib(afxglobals.ob<wbr />j) : error LNK2005: &quot;public: virtual __thiscall CMemDC::~CMemDC(void)&quot; (??1CMemDC@@UAE@XZ) already defined in WaveFormDialog.obj<br />
5&gt;.\Release/Book.exe : fatal error LNK1169: one or more multiply defined symbols found<br />
<br />
I didn't do any changes at all. Just rebuilt the project. Could you please tell me how I could fix that?<br />
CMemDC::~CMemDC(void) is defined in MemDC.h, and WaveFormDialog.cpp has<br />
#include &quot;MemDC.h&quot;
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Dear experts,

My application worked fine, but suddenly started giving me 

5>nafxcw.lib(afxglobals.obj) : error LNK2005: "public: virtual __thiscall CMemDC::~CMemDC(void)" (??1CMemDC@@UAE@XZ) already defined in WaveFormDialog.obj
5>.\Release/Book.exe : fatal error LNK1169: one or more multiply defined symbols found

I didn't do any changes at all. Just rebuilt the project. Could you please tell me how I could fix that?
CMemDC::~CMemDC(void) is defined in MemDC.h, and WaveFormDialog.cpp has
#include "MemDC.h"

MFC: linking error

C++ is an intermediate-level general-purpose programming language, not to be confused with C or C#. It was developed as a set of extensions to the C programming language to improve type-safety and add support for automatic resource management, object-orientation, generic programming, and exception handling, among other features.