我正在读一本关于C ++的书。我还是很公平,但我仍然在努力完成细节。这一部分涉及继承,目标是制作一个形状类,然后用第一个二维形状构建到它上面,然后用二维形状构建三维形状。
到目前为止,我已经能够一路上升并完成二维形状。那里的功能很好。我现在已经转向了三维形状,这就是我遇到一些问题的地方。
这本书说实现一个允许长度,高度和三维宽度的系统是整数或浮点数,所以我已经在其中放置了一个模板来做到这一点。这就是我认为我遇到问题的地方。
我确实将二维类复制并复制到三维类中并尝试从那里完成它。然后我把它运行到了一点问题。
当我尝试编译时,我得到两个主要错误。
错误:' ThreeD'不是类模板 错误:显式实例化非模板类型' ThreeD'
我认为是需要提交相关信息的最小部分。请记住,main.cpp,shape.h,shape.cpp,twod.h和twod.cpp可以正常工作,但我已经包含了完整的标题而不是完整的其他cpps。
你能提供的任何帮助都会很棒。
我已将ThreeD.cpp置于顶部,因为错误来自此处。
我不认为它是"为什么模板只能在头文件中实现?"因为代码适用于TwoD类,而不是ThreeD类。
ThreeD.cpp
#include <iostream>
#include <string>
#include "shape.h"
#include "TwoD.h"
using namespace std;
template class ThreeD<int>;
template class ThreeD<float>;
template <class T>
ThreeD<T>::ThreeD (string oobj, int osides, T olength, T oheight, T owidth)
: TwoD<T>(oobj, osides, olength, oheight)
{
setObject(obj);
setSides(sides);
setLength(length);
setHeight(height);
setWidth(owidth);
} //End of TwoD constructor
template <class T>
int ThreeD<T>::getSides() {
return sides;
} //End of function getSides
的main.cpp
#include <iostream>
#include "shape.h"
#include "TwoD.h"
#include "ThreeD.h"
using namespace std;
int main() {
TwoD<float> triangle("Triangle", 3, 3, 3);
ThreeD<float> cube("Cube", 6, 3, 3, 3);
}
Shape.h
#ifndef SHAPE_H
#define SHAPE_H
#include <string>
using namespace std;
//Implimenting template <class T> as a means to have the sides
//variable become either a float or an int.
template <class T>
class Shape {
public:
Shape(string, int, T);
// void setObject(string); //Used to ensure constructor works
virtual void setObject(string) = 0;
//Used setObject as virtual function since constructor uses it to
//Make the object using the setObject function.
string getObject();
int getSides();
bool setSides(int);
float getLength();
void setLength (T);
float getPerimeter(string, T);
float getArea (string, T);
void display();
private:
string object;
int sides;
T length;
};
#endif
Shape.cpp
#include <iostream>
#include <string>
#include "shape.h"
using namespace std;
//Telling the compiler template class of Shape which versions for T to
//expect either int or float.
template class Shape<int>;
template class Shape<float>;
//Constructor of Shape. Inputs shape, sides, and length.
template <class T>
Shape<T>::Shape (string shapes, int sides, T length){
setObject(shapes);
setSides(sides);
setLength(length);
} //End of Shape constructor
TwoD.h
#ifndef TWOD_H
#define TWOD_H
#include <string>
#include "shape.h"
using namespace std;
//Implimenting template <class T> as a means to have the sides
//variable become either a float or an int.
template <class T>
class TwoD : public Shape<T>
{
public:
TwoD(std::string, int, T, T);
void setObject(string); //Used to ensure constructor works
// virtual void setObject(string) = 0;
//Used setObject as virtual function since constructor uses it to
//Make the object using the setObject function.
string getObject();
int getSides();
bool setSides(int);
T getLength();
void setLength (T);
T getHeight();
void setHeight (T);
float getPerimeter(string, T, T);
float getArea (string, T, T);
void display();
private:
string object;
int sides;
T length;
T height;
};
#endif
TwoD.cpp
#include <iostream>
#include <string>
#include "shape.h"
#include "TwoD.h"
using namespace std;
//Telling the compiler template class of TwoD which versions for T to
//expect either int or float.
template class TwoD<int>;
template class TwoD<float>;
//Constructor of TwoD. Inputs TwoD, sides, and length.
template <class T>
TwoD<T>::TwoD (string obj, int sides, T length, T height)
: Shape<T>(obj, sides, length)
{
setObject(obj);
setSides(sides);
setLength(length);
setHeight(height);
} //End of TwoD constructor
ThreeD.h
#ifndef THREED_H
#define THREED_H
#include <string>
#include "shape.h"
#include "TwoD.h"
using namespace std;
//Implimenting template <class T> as a means to have the sides
//variable become either a float or an int.
template <class T>
class ThreeD : public TwoD<T>
{
public:
ThreeD(std::string, int, T, T, T);
void setObject(std::string); //Used to ensure constructor works
// virtual void setObject(string) = 0;
//Used setObject as virtual function since constructor uses it to
//Make the object using the setObject function.
string getObject();
int getSides();
bool setSides(int);
T getLength();
void setLength (T);
T getHeight();
void setHeight (T);
T getWidth();
void setWidth (T);
float getPerimeter(string, T, T, T);
float getArea (string, T, T, T);
void display();
private:
std::string object;
int sides;
T length;
T height;
T width;
};
#endif
答案 0 :(得分:1)
在ThreeD.cpp
中你需要:
#include "ThreeD.h"
没有它,行template class ThreeD<int>;
对编译器没有意义,因为ThreeD
尚未声明。