調用從類C++函數

Question

頭文件是這樣的：

#include "Lib110ct.h" 
class Circle 
{ 
protected: 
    double mx, my, mdx, mdy, mradius; 
public: 
    Circle(){} 
    Circle(double x,double y,double dx,double dy,double rad):mx(x),my(y),mdx(dx),mdy(dy),mradius(rad){} 
    void setPos(double x, double y){mx=x;my=y;} 
    void setDir(double dx, double dy){mdx=dx; mdy=dy;} 
    void setRadius(double rad){mradius=rad;} 
    double getX(){return mx;} 
    double getY(){return my;} 

    void draw(Turtle * t); 
    void clear(Win110ct& win); 
    void move(); 
    bool collides(Circle & c); 
}; 

#include "shape.h" 

int main(int argc, char** argv) 

    { 
     Win110ct win; 
     Turtle * t = win.getTurtle(); 
      Circle Circle; 
      Circle.setPos(100, 300); 
      Circle.setRadius(12); 
      getX(); 
      getY(); 
      Circle.draw(t); 

     return 0; 
    } 

它給我的錯誤信息是：

C：\用戶\ Oluwaseun \文檔\ 110ct \ challenge2 \ programming \ programming \ main.cpp | 13 |對`Circle :: draw（Turtle *）'|的未定義引用

我在做什麼錯？

Answer 1

您需要定義

void draw(Turtle * t); 

請大家在看看：http://www.cprogramming.com/declare_vs_define.html

基本上，你定義一個函數，當你爲它編寫代碼：

void draw(Turtle* t) { 
    // code here 
}