Question

我有一个抽象的基类“家具”，有1个子类“书柜”。

在handler.cpp中我创建了双指针;家具**家具。所以当我想添加东西时，我可以使用这样的东西;

void FurnitureHandler::addBookcase(string name, float price, int stock, string material, float height)
{
    this->furniture[this->nrOfFurniture] = new Bookcase(name, price, stock, material, height);
    this->nrOfFurniture++;
}

然而，“新”突出显示，我得到'错误C2243：'类型转换'：从'书柜*'到'家具*'的转换存在，但是无法访问'。我需要做些什么来使其发挥作用？

码;

#ifndef __FURNITURE_H__
#define __FURNITURE_H__

#include<string>
#include<iostream>
using namespace std;

class Furniture
{
private:
    string name;
    float price;
    int stock;
public:
    void print()const;
    virtual void printSpec()const =0;

public:
    Furniture(string name = "", float price = 0.0f, int stock = 0);
    virtual ~Furniture();
};

#endif


Furniture::Furniture(string name, float price, int stock)
{
    this->name=name;
    this->price=price;
    this->stock=stock;
}

Furniture::~Furniture(){}

void Furniture::print()const
{
    cout<<"All furnitures in memory:"<<endl;
    this->printSpec();
}


#ifndef __BOOKCASE_H__
#define __BOOKCASE_H__

#include "Furniture.h"

class Bookcase : Furniture
{
private:
    string material;
    float height;
public:
    Bookcase(string, float, int, string, float);
    virtual ~Bookcase();
    virtual void printSpec()const;
};

#endif

#include "Bookcase.h"

Bookcase::Bookcase(string name, float price, int stock, string material, float height) : Furniture(name, price, stock)
{
    this->material = material;
    this->height = height;
}

Bookcase::~Bookcase(){}

void Bookcase::printSpec()const
{
    cout<<material<<", "<<height<<endl;
}

Answer 1

更新

class Bookcase : Furniture

到

class Bookcase : public Furniture

默认情况下，C ++是私有继承的，这使得Bookcase has a Furniture。

当您添加public inheritance时，会生成Bookcase is a Furniture

Answer 2

您使用的是私有而非公共继承，因此转换不是隐含的。

你必须写：

class Bookcase : public Furniture
//               ^^^^^^

这类似于会员，默认情况下这些会员是私人的，除非您说public。

如果使用Bookcase关键字声明struct，则默认为公开。

此外，使用std::vector而不是这种危险的内存管理，你会好得多。

Answer 3

使用Furniture**使用this->furniture[this->nrOfFurniture] = ...是危险的，因为在我看来，您不会检查是否可以插入最大数量的Furniture（{1}}你可能会覆盖你不拥有的内存。最好有std::vector个push_back元素。

c ++使用子类'type cast'错误

3 个答案: