我有一个 Unresolved external symbol 错误,这让我很抓狂。简而言之,我有一个 SDL_Surfaces ('DgSurface') 的包装类和一个用于加载和存储 DgSurfaces ('DgSurfaceList') 的类。尝试在我的项目中包含 DgSurfaceList 文件时出现链接问题。这是我的类(class):
头文件“DgSurface.h”包含 DgSurface 类声明:
#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 定义:
#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;
}
这门课似乎工作正常并按预期执行(但是,一如既往,我愿意接受反馈:)。
“DgSurfaceList.h”包含 DgSurfaceList 类声明:
#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 定义:
#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()
现在,如果我注释掉 cpp 文件中的 DgSurfaceList::GetImage() 定义,DgSurfaceList 似乎可以正常工作并正确存储图像。更具体地说,只有当我在上述函数中包含 for 循环时才会出现链接错误。会是什么呢?
其他信息:
错误:
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 "
编码环境:
Visual C++ Express 2010
最佳答案
CrtDbgReport 仅在 C 运行时库的调试版本中定义。因此,也许您是在 Debug模式下进行编译,但与该库的发行版链接。另一种可能性是您在 Release模式下编译,但您定义的某些宏导致编译 std::list 的调试版本。
关于c++ - Unresolved external ,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/11919836/