C ++ lnk错误2019未解决的外部符号虚拟错误，因为一个接口...（？） [英] C++ lnk error 2019 unresolved external symbol virtual errors because of an interface...(?)

问题描述

我有一个良好的接口，使用它有问题...
我的设置概述：

一个接口 GraphicsLibrary.H ...

  virtual void drawPoint（const Point& p，unsigned char r，unsigned char g，unsigned char b，double pointSize）; 
  

使用空GraphicsLibrary.ccp！因为它的一个接口，所以OpenGL是一个图形库...所以我有一个 OpenGL.CPP ：

  void GraphicsLibrary :: drawPoint（const Point& p，unsigned char r，unsigned char g，unsigned char b，double pointSize）
 {
 //一些代码
} 
  

其中有一个空OpenGL.h（因为他的头文件是GraphicsLibrary.h）

那么我有一个更具体的函数使用OpenGL的类，并使用这些基本绘图函数...（ OpenGLVis_Enviroment.cpp ）：

  OpenGL ogl; 
 void drawObstacleUnderConstruction（Obstacle :: Type type，const vector< Point>& points）
 {
 for（// etcetc）
 ogl.drawPoint（* it， 255，255，3.0）; 
} 
  

但我也有一个主要使用一些OpenGL函数...
因此 main 也具有：

  OpenGL openGL; 
 openGL.drawText（something）; 
  

但现在我有很多错误（我有所有其他功能相同）：

  1> OpenGLVis_Environment.obj：error LNK2019：未解析的外部符号public：virtual void __thiscall GraphicsLibrary :: drawPoint函数void __cdecl DrawingFunctions :: drawObstacleUnderConstruction（enum Obstacle :: Type，class std ::）中引用的&，unsigned char，unsigned char，unsigned char，double）（？drawPoint @ GraphicsLibrary @@ UAEXABUPoint @@ EEEN @矢量< struct Point，class std :: allocator< struct Point> const&）（？drawObstacleUnderConstruction @ DrawingFunctions @@ YAXW4Type @ Obstacle @@ ABV？$ vector @ UPoint @@ V？$ allocator @ UPoint @@@这是因为我使用了GraphicsLibrary :: drawPoint。这是因为我们使用了GraphicsLibrary :: drawPoint。 ..？我在网上搜索年龄，但很难找到很多关于接口的例子和如何使用它们... 
感谢在先人们
解决方案
链接器提出 DrawingFunctions :: drawObstacleUnderConstruction ，并定义 void drawObstacleUnderConstruction  
 
  void DrawingFunctions :: drawObstacleUnderConstruction（Obstacle :: Type type，const vector< Point>& points）
 {
 for（// etcetc）
 ogl.drawPoint * it，255，255，255，3.0）; 
} 
  
 
Im having problems with making a good interface and use it...
My setup overview:

An "interface" GraphicsLibrary.H...
virtual void drawPoint(const Point& p, unsigned char r, unsigned char g, unsigned char b, double pointSize);
with an "empty" GraphicsLibrary.ccp! because its an interface, so "OpenGL" is an graphics library... so i have an OpenGL.CPP with:
void GraphicsLibrary::drawPoint(const Point& p, unsigned char r, unsigned char g, unsigned char b, double pointSize)
{
    //some code
}
which has ofcourse an "empty" OpenGL.h (since his header file is the GraphicsLibrary.h)

then i have a class with more specific functions that uses OpenGL, and uses those base drawing functions... (OpenGLVis_Enviroment.cpp):
OpenGL ogl;
void drawObstacleUnderConstruction(Obstacle::Type type, const vector<Point>& points)
{
for( //etcetc )
        ogl.drawPoint(*it, 255, 255, 255, 3.0);
}
BUT i also have a main that uses some OpenGL functions...
so the main has also:
OpenGL openGL;
openGL.drawText(something);
but now i have a lot of those errors (i have the same with all the other functions):
1>OpenGLVis_Environment.obj : error LNK2019: unresolved external symbol "public: virtual void __thiscall GraphicsLibrary::drawPoint(struct Point const &,unsigned char,unsigned char,unsigned char,double)" (?drawPoint@GraphicsLibrary@@UAEXABUPoint@@EEEN@Z) referenced in function "void __cdecl DrawingFunctions::drawObstacleUnderConstruction(enum Obstacle::Type,class std::vector<struct Point,class std::allocator<struct Point> > const &)" (?drawObstacleUnderConstruction@DrawingFunctions@@YAXW4Type@Obstacle@@ABV?$vector@UPoint@@V?$allocator@UPoint@@@std@@@std@@@Z)
Is this because i use "GraphicsLibrary::drawPoint..." ? I am searching online for ages, but  it's hard to find a lot of examples about interfaces.. and how to work with them... 
Thanks in advance guys
解决方案
The linker complains about DrawingFunctions::drawObstacleUnderConstruction and you defined void drawObstacleUnderConstruction, which is a free function.

Qualify the name when you define the function.
void DrawingFunctions::drawObstacleUnderConstruction(Obstacle::Type type, const vector<Point>& points)
{
    for( //etcetc )
        ogl.drawPoint(*it, 255, 255, 255, 3.0);
}


                        
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