Question

#include <iostream>
using namespace std;

class Item {
private:
    int _code;
    int _color;
    int _brand;
    double _height;
    double _length;
    double _width;
    double _weight;
    double _price;
    int _type;
    bool _doesItHaveThis;

public:
    Item();
    Item(int code, int color, int brand, double height, double length, double width,
        double weight, double price, int type, bool doesItHaveThis);
    void setCode(int code);
    void setColor(int color);
    void setBrand(int brand);
    void setHeight(double height);
    void setLength(double length);
    void setWidth(double width);
    void setWeight(double weight);
    void setPrice(double price);
    void setType(int type);
    void setDoesItHaveThis(bool doesItHaveThis);
    int getCode();
    int getColor();
    int getBrand();
    double getHeight();
    double getLength();
    double getWidth();
    double getWeight();
    double getPrice();
    int getType();
    bool getDoesItHaveThis();
    virtual ~Item();
    void display();
};
//----------------------------------------------------------
Item::Item()
{
    _code = 0;
    _color = 0;
    _brand = 0;
    _height = 0;
    _length = 0;
    _width = 0;
    _weight = 0;
    _price = 0;
    _type = 0;
    _doesItHaveThis = 0;
}
//----------------------------------------------------------
Item::Item(int code, int color, int brand, double height, double length, double width,
    double weight, double price, int type, bool doesItHaveThis)
{
    _code = code;
    _color = color;
    _brand = brand;
    _height = height;
    _length = length;
    _width = width;
    _weight = weight;
    _price = price;
    _type = type;
    _doesItHaveThis = doesItHaveThis;
}
//----------------------------------------------------------
void Item::setCode(int code)
{
    _code = code;
}
//----------------------------------------------------------
void Item::setColor(int color)
{
    _color = color;
}
//----------------------------------------------------------
void Item::setBrand(int brand)
{
    _brand = brand;
}
//----------------------------------------------------------
void Item::setHeight(double height)
{
    _height = height;
}
//----------------------------------------------------------
void Item::setLength(double length)
{
    _length = length;
}
//----------------------------------------------------------
void Item::setWidth(double width)
{
    _width = width;
}
//----------------------------------------------------------
void Item::setWeight(double weight)
{
    _weight = weight;
}
//----------------------------------------------------------
void Item::setPrice(double price)
{
    _price = price;
}
//----------------------------------------------------------
void Item::setType(int type)
{
    _type = type;
}
//----------------------------------------------------------
void Item::setDoesItHaveThis(bool doesItHaveThis)
{
    _doesItHaveThis = doesItHaveThis;
}
//----------------------------------------------------------
int Item::getCode()
{
    return _code;
}
//----------------------------------------------------------
int Item::getColor()
{
    return _color;
}
//----------------------------------------------------------
int Item::getBrand()
{
    return _brand;
}
//----------------------------------------------------------
double Item::getHeight()
{
    return _height;
}
//----------------------------------------------------------
double Item::getLength()
{
    return _length;
}
//----------------------------------------------------------
double Item::getWidth()
{
    return _width;
}
//----------------------------------------------------------
double Item::getWeight()
{
    return _weight;
}
//----------------------------------------------------------
double Item::getPrice()
{
    return _price;
}
//----------------------------------------------------------
int Item::getType()
{
    return _type;
}
//----------------------------------------------------------
bool Item::getDoesItHaveThis()
{
    return _doesItHaveThis;
}
//----------------------------------------------------------
Item::~Item()
{
    cout << "ITEM ELIMINATED" << endl;
}
//----------------------------------------------------------
void Item::display()
{
    cout << "code = " << _code << ", color = " << _color << ", brand = "
         << _brand << ", height = " << _height << ", length = " << _length
         << ", width = " << _width << ", weight = " << _weight << ", price = "
         << _price << ", type = " << _type << ", doesItHaveThis = "
         << _doesItHaveThis << endl;
}
//----------------------------------------------------------
class Pens : public Item {
private:
    int _code;
    int _color;
    int _brand;
    double _height;
    double _length;
    double _width;
    double _weight;
    double _price;
    int _type;
    bool _doesItHaveThis;
    int _packetSize;

public:
    Pens();
    Pens(int code, int color, int brand, double height, double length, double width,
        double weight, double price, int type, bool doesItHaveThis, int packetSize);
    void setPacketSize(int packetSize);
    int getPacketSize();
    virtual ~Pens();
    void display();
};
//----------------------------------------------------------
Pens::Pens()
{
    _code = 0;
    _color = 0;
    _brand = 0;
    _height = 0;
    _length = 0;
    _width = 0;
    _weight = 0;
    _price = 0;
    _type = 0;
    _doesItHaveThis = 0;
    _packetSize = 0;
}
//----------------------------------------------------------
Pens::Pens(int code, int color, int brand, double height, double length, double width,
    double weight, double price, int type, bool doesItHaveThis, int packetSize)
{
    _code = code;
    _color = color;
    _brand = brand;
    _height = height;
    _length = length;
    _width = width;
    _weight = weight;
    _price = price;
    _type = type;
    _doesItHaveThis = doesItHaveThis;
    _packetSize = packetSize;
}
//----------------------------------------------------------
void Pens::setPacketSize(int packetSize)
{
    _packetSize = packetSize;
}
//----------------------------------------------------------
int Pens::getPacketSize()
{
    return _packetSize;
}
//----------------------------------------------------------
Pens::~Pens()
{
    cout << "PEN ELIMINATED" << endl;
}
//----------------------------------------------------------
void Pens::display()
{
    cout << "code = " << _code << ", color = " << _color << ", brand = "
         << _brand << ", height = " << _height << ", length = " << _length
         << ", width = " << _width << ", weight = " << _weight << ", price = "
         << _price << ", type = " << _type << ", doesItHaveThis = "
         << _doesItHaveThis << ", packetSize = " << _packetSize << endl;
}
//----------------------------------------------------------
void main()
{
    Pens I1(1, 2, 3, 4.1, 2.0, 3.4, 3.3, 3.2, 5, 1, 0);
    I1.setBrand(999);
    I1.setDoesItHaveThis(0);
    I1.setHeight(34.62);
    I1.display();
}

所以这是我的代码，我想知道为什么Pens类没有正确继承Item类的公共方法。当我运行这段代码时，setBrand（999），setDoesItHaveThis和setHeight不能从输出中看出来。谁能说出我做错了什么？

Answer 1

使用多态的方法是继承基类的成员。如果你改为重复它们，那么这将声明同名的另一个成员。

derived

此处，member1有两个成员base：一个继承自<xsl:for-each-group select="tr" group-by="td[1]">，另一个未继承。程序员（但不是编译器）很容易混淆这两个。所以应该避免使用这样的结构（好的编译器会警告你）。

Answer 2

在派生类中，使用您需要的所有参数调用基类构造函数。并且像注释中指出的那样，不要将所有基类变量重新声明为派生类的新成员。要设置/获取基类成员变量，请使用在基类中公开的Setters和Getters（这些由派生类继承）。（如果我是你，我会保护二传手）。还要查看构造函数中的初始化列表，而不是初始化正文中的每个成员 - Read this

C ++继承无法正常工作

2 个答案: