未解決的外部

Question

我有一個無法解決的外部符號錯誤，這使我發瘋。 簡而言之，我有一個SDL_Surfaces包裝類（“ DgSurface”）和一個用於加載和存儲DgSurfaces的類（“ DgSurfaceList”）。 嘗試在我的項目中包含DgSurfaceList文件時出現鏈接問題。 這是我的課程：

頭文件“ DgSurface.h”包含DgSurface類聲明：

    #ifndef DGSURFACE_H
    #define DGSURFACE_H

    #include "SDL.h"
    #include <string>

    class DgSurface
    {
    public:

        //Constructor/destructor
        DgSurface(std::string N, SDL_Surface* I): image(I), name(N) {}
        DgSurface() {name = ""; image = NULL;}
        ~DgSurface();

        //Copy operations
        DgSurface(const DgSurface&);
        DgSurface& operator= (const DgSurface&);

        //Data members
        std::string name;       //The name of the image
        SDL_Surface* image;     //The image
    };

    #endif

cpp文件“ DgSurface.cpp”包含DgSurface定義：

#include "DgSurface.h"
#include "SDL.h"

//--------------------------------------------------------------------------------
//        Constructor
//--------------------------------------------------------------------------------
DgSurface::DgSurface(const DgSurface& other)
{
    //Copy name
    name = other.name;

    //Create new SDL_Surface 
    image = SDL_ConvertSurface(other.image, other.image->format, 0);
}


//--------------------------------------------------------------------------------
//        Destructor
//--------------------------------------------------------------------------------
DgSurface::~DgSurface()
{
    SDL_FreeSurface(image);
}


//--------------------------------------------------------------------------------
//        Assignment operator
//--------------------------------------------------------------------------------
DgSurface& DgSurface::operator= (const DgSurface& other)
{
    // if same object
    if ( this == &other )
        return *this;

    //Copy name
    name = other.name;

    //Create new SDL_Surface 
    image = SDL_ConvertSurface(other.image, other.image->format, 0);

    return *this;
}

該課程似乎運行良好，並且按預期方式運行（但是，一如既往，我們隨時可以提供反饋意見：）。

“ DgSurfaceList.h”包含DgSurfaceList類聲明：

#ifndef DGSURFACELIST_H
#define DGSURFACELIST_H

#include "SDL.h"
#include <list>
#include <string>
#include "DgSurface.h"


class DgSurfaceList
{
    public:
        //Constructors/destructor
        DgSurfaceList() {}
        ~DgSurfaceList() {}

        //Functions
        bool AddImage(std::string location, std::string name);

        //Return Functions
        SDL_Surface* GetImage(std::string S) const;

    private:
        //Data members
        std::list<DgSurface> imlist;    //The list of DgSurfaces

        //Functions
        SDL_Surface* LoadImage( std::string filename );
};


#endif

最后，“ DgSurfaceList.cpp”包含DgSurfaceList定義：

#include "SDL.h"
#include "SDL_image.h"
#include <list>
#include <string>
#include "DgSurface.h"
#include "DgSurfaceList.h"


//--------------------------------------------------------------------------------
//      Load an image from file
//--------------------------------------------------------------------------------
SDL_Surface* DgSurfaceList::LoadImage( std::string filename )
{
    //Loads an image from file, returns SDL_surface*
    ...

}   //End:DgSurfaceList::LoadImage()


//--------------------------------------------------------------------------------
//      Add a DgSurface to the list
//--------------------------------------------------------------------------------
bool DgSurfaceList::AddImage(std::string location, std::string name) 
{
    //Load the image
    DgSurface temp(name,LoadImage(location));

    //If there was an error in loading the image
    if( temp.image == NULL )
        return false;

    //If everything loaded fine, place a copy into imlist
    imlist.push_back(temp);

    return true;

}   //End: DgSurfaceList::AddImage();


//--------------------------------------------------------------------------------
//      Searches imlist for an image, returns a pointer to a SDL_Surface
//--------------------------------------------------------------------------------
SDL_Surface* DgSurfaceList::GetImage(std::string S) const
{
    std::list<DgSurface>::const_iterator i;

    //Search imlist for DgSurface of the same name
    for (i = imlist.begin(); i != imlist.end(); i++)
    {
        if (S.compare((*i).name) == 0)
            return (*i).image;
    }

    //Return Null if name not found
    return NULL;

}   //End:DgSurfaceList::GetImage()

現在，如果我注釋掉cpp文件中的DgSurfaceList :: GetImage（）定義，則DgSurfaceList似乎可以正常工作並正確存儲圖像。 更具體地說，僅當我在上述函數中包含for循環時，才會出現鏈接錯誤。 會是什么呢？

其他資訊：

錯誤：

unresolved external symbol __imp___CrtDbgReportW referenced in function "public: class 
DgSurface const & __thiscall std::_List_const_iterator<class std::_List_val<class 
DgSurface,class std::allocator<class DgSurface> > >::operator*(void)const "

編碼環境：Visual C ++ Express 2010

Answer 1

CrtDbgReport僅在C運行時庫的調試版本中定義。 因此，也許您是在調試模式下進行編譯，但與庫的發行版鏈接。 另一種可能性是您正在發布模式下進行編譯，但是您定義的某些宏正在導致編譯std :: list的調試版本。