c++ - 无缘无故的多重析构函数定义

Question

我有一个项目要从 VC6 迁移到 VS2013。在构建项目时，出现此错误。

error LNK2005: "public: virtual __thiscall CMemDC::~CMemDC(void)" (??1CMemDC@@UAE@XZ) already defined in GameBoard.obj

以下是可能导致此问题的文件。

GameBoard.h

#include "DirectSound.h"
#include "MIDI.h"
#include <vector>
class CGameBoard : public CWnd
{
    friend class CTetrisDlg;
    friend class COptionsDlg;

    DECLARE_DYNAMIC(CGameBoard);

// Construction/Destruction
public:
    CGameBoard();
    virtual ~CGameBoard();

.......
};

GameBoard.cpp 文件具有此析构函数的定义。

#include "stdafx.h"
#include "Tetris.h"
#include "GameBoard.h"
#include "Piece.h"
#include "MemDC.h"
#include "VolumeCtrl.h"

#include <stdlib.h>
#include <time.h>
static CGameBoard * gpGameBoard;

CGameBoard::CGameBoard()
{
    m_pCurPiece = m_pNextPiece = 0;
    m_usLevel = 0;
    m_clrCurPiece = RGB(0,0,0);
    m_bShowGrid = TRUE;
    m_nSquareWidth = 14;
    m_nSquareHeight = 14;
    m_clrBackground = RGB(255, 255, 255);
    m_bExFigures = FALSE;
    m_pMusic = 0;
    m_uTimer = 0;
    m_dwVolume = 100;   // 100% music volume by default

    gpGameBoard = this;
}

CGameBoard::~CGameBoard()
{
    if(m_pCurPiece)
        delete m_pCurPiece;
    if(m_pNextPiece)
        delete m_pNextPiece;

    if( m_pMusic )
        delete m_pMusic;

    gpGameBoard = 0;
}

此析构函数仅在 GameBoard.cpp 中定义一次，并且 GameBoard 不包含在任何其他 cpp 或 头文件。

MemDC.h

#ifndef _MEMDC_H_
#define _MEMDC_H_

class CMemDC : public CDC {
private:
    CBitmap m_bitmap;       // Offscreen bitmap
    CBitmap* m_oldBitmap;   // bitmap originally found in CMemDC
    CDC* m_pDC;             // Saves CDC passed in constructor
    CRect m_rect;           // Rectangle of drawing area.
    BOOL m_bMemDC;          // TRUE if CDC really is a Memory DC.

public:
    CMemDC(CDC* pDC) : CDC(), m_oldBitmap(NULL), m_pDC(pDC)
    {
        ASSERT(m_pDC != NULL); // If you asserted here, you passed in a NULL CDC.

        m_bMemDC = !pDC->IsPrinting();

        if (m_bMemDC){
            // Create a Memory DC
            CreateCompatibleDC(pDC);
            pDC->GetClipBox(&m_rect);
            m_bitmap.CreateCompatibleBitmap(pDC, m_rect.Width(), m_rect.Height());
            m_oldBitmap = SelectObject(&m_bitmap);
            SetWindowOrg(m_rect.left, m_rect.top);
        } else {
            // Make a copy of the relevent parts of the current DC for printing
            m_bPrinting = pDC->m_bPrinting;
            m_hDC = pDC->m_hDC;
            m_hAttribDC = pDC->m_hAttribDC;
        }
    }

    ~CMemDC()
    {
        if (m_bMemDC) {
            // Copy the offscreen bitmap onto the screen.
            m_pDC->BitBlt(m_rect.left, m_rect.top, m_rect.Width(), m_rect.Height(),
                            this, m_rect.left, m_rect.top, SRCCOPY);
            //Swap back the original bitmap.
            SelectObject(m_oldBitmap);
        } else {
            // All we need to do is replace the DC with an illegal value,
            // this keeps us from accidently deleting the handles associated with
            // the CDC that was passed to the constructor.
            m_hDC = m_hAttribDC = NULL;
        }
    }

    // Allow usage as a pointer
    CMemDC* operator->() {return this;}

    // Allow usage as a pointer
    operator CMemDC*() {return this;}
};

#endif

此问题与一个定义规则相关，该规则定义为 here ，但我不知道该怎么做。

我做了一些修改建议here .现在我遇到了以下错误。有什么想法吗？

error LNK1181: cannot open input file 'Nafxcwd.lib Libcmtd.lib'

Answer 1

好吧，终于按照设置帮助我解决了这个问题..

1. Project properties->linker->input->ignore specific default library ..设置为.. nafxcw.lib libcmt.lib
2. 项目属性->c/c++->代码生成->运行时库 ..设置为.. 多线程DLL(/MD)
3. Project properties->configuration properties->general->Use of MFC .. set to .. use of MFC in a shared DLL.

除了这些设置之外，我没有更改任何代码(w.r.t. 包括守卫等)