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我正在努力使用继承。我正在学习计算机科学并且必须解决它... Rihgt 现在我正在尝试制作我自己的“复制”类，其中包含对“可绘制”对象的引用，例如我有一个“圆圈”类的对象' 继承自 'Drawable'。我想复制上述对象“圆圈”，这似乎可以。但是当我想调用“draw”方法时，事情就变糟了。

错误信息：

1>------ Build started: Project: Project2, Configuration: Debug Win32 ------  
1>  main.cpp  
1>  Drawable.cpp  
1>  copy.cpp  
1>  Cirkel.cpp  
1>  Generating Code...  

1>Cirkel.obj : error LNK2001: unresolved external symbol "public: virtual void __thiscall Drawable::draw(class sf::RenderWindow &,class sf::Vector2<float>)" (?draw@Drawable@@UAEXAAVRenderWindow@sf@@V?$Vector2@M@3@@Z)  

1>copy.obj : error LNK2001: unresolved external symbol "public: virtual void __thiscall Drawable::draw(class sf::RenderWindow &,class sf::Vector2<float>)" (?draw@Drawable@@UAEXAAVRenderWindow@sf@@V?$Vector2@M@3@@Z)

**这是我的主要内容：**

#include <SFML\Graphics>
#include "circle.hpp"
#include "copy.hpp"


int main(){

    sf::RenderWindow window{ sf::VideoMode{ 640, 480 }, "SFML window" };

    circle blauwe_circle{ 40.0F, sf::Color::Blue };
    circle rode_circle{ 10.F, sf::Color::Red };

    copy cBlauw{ sf::Vector2f{ 40.f, 40.f }, blauwe_circle };
    copy cRoodA{ sf::Vector2f{ 50.f, 50.f }, rode_circle };

    sf::Vector2f nul{ 0.f, 0.f };



    while (window.isOpen()){

        sf::Event event;
        while (window.pollEvent(event)){
            if (event.type == sf::Event::Closed) window.close();
        }
        sf::sleep(sf::milliseconds(20));
    }
    return 0;
}`

可绘制的.hpp

class Drawable
{
    public:
        virtual void draw(sf::RenderWindow & window, sf::Vector2f vector);
};

圈子.hpp：

#include "Drawable.hpp"

class circle : public Drawable{

    public:

    circle(float size = 30, sf::Color color = sf::Color::Red);

    void draw(sf::RenderWindow & window, sf::Vector2f position) override;

    private:

    float size;
    sf::Color color;
    sf::CircleShape c;

};

圆环.cpp

#include "circle.hpp"
#include "Drawable.hpp"

circle::circle(float fSize, sf::Color color) :
    size{ fSize },
    color{ color }
{
    c.setRadius(size);
    c.setPointCount(30U);
    c.setFillColor(color);
}

void circle::draw(sf::RenderWindow & window, sf::Vector2f position){
    c.setPosition(position);
    window.draw(c);
}

复制.hpp：

#include "Drawable.hpp"

class copy: public Drawable
{
    public:
        copy(sf::Vector2f position, Drawable & c);
        void draw(sf::RenderWindow & window, sf::Vector2f vector) override;
    private:
        sf::Vector2f position;
        Drawable & c;
};

复制.cpp

#include "copy.hpp"
#include "Drawable.hpp"

copy::copy(sf::Vector2f vPosition, Drawable & c) :
    position{ vPosition },
    c{ c }
{}

void copy::draw(sf::RenderWindow & window, sf::Vector2f v){
    c.draw(window, v);
}
4

1 回答 1

2

如果Drawable::draw打算成为一个没有实现的纯虚函数，请添加= 0：

class Drawable
{
    public:
        virtual void draw(sf::RenderWindow & window, sf::Vector2f vector) = 0;
};
于 2014-09-15T18:22:10.200 回答