Question

提出的问题：

将以下功能添加到问题5的Shape类：

两个私有静态成员shapesCreated和shapesDestroyed，分别用于计算已创建和销毁的Shape对象的总数。析构函数，它增加shapesDestroyed的值修改类构造函数，以便每次创建新的Shape对象时它都会增加shapesCreated变量。静态方法static int shapesCount（），返回仍然活动的当前Shape对象数。将shapeID（非静态）成员添加到Shape类，该类是形状的唯一整数id。使用构造上的shapesCreated值设置它的值，也就是说，创建的第n个形状的id值等于n。添加方法int id（）以返回Shape对象的id。 [15分]

Q7。编写两个继承自Shape的Circle和Rectangle类，并根据需要正确实现其构造函数以设置其半径/坐标。它们还必须实现从Shape继承的info（）方法。他们的info（）方法应返回一个字符串，其中包含形状的id，形状的坐标信息和形状的颜色。

[15分]

我的代码：

#include <iostream>
#include <sstream>
using namespace std;
int shapeIDCounter = 0,createDestroyCounter=0;

class Colour{
    private:
        double red,blue,green;

    public:
        double rMax;


        Colour(double a,double b,double c){
            red = a;
            blue = b;
            green = c;


        }
        // #1
        Colour(const Colour& clr){
            red = clr.r();
            blue = clr.b();
            green = clr.g();
            cout << "\nConstructed colour by copying anothers properties";
        }

        double r() const {
            return red;
            }

        double b() const {
            return blue;
            }

        double g() const {
            return green;
            }

        string toString(){
        string info = "The value for the colour components are: (";
        ostringstream convertR;
        convertR << r();
        info += convertR.str();
        ostringstream convertB;
        info += ",";
        convertB << b();
        info += convertB.str();
        ostringstream convertG;
        info += ",";
        convertG << g();
        info += convertG.str();
        info += ")";
        return info;
        }

        static Colour maxRed(Colour carr[], int size){
            double rMax;
            rMax = carr[0].r(); //initial case of first element
            for(int i = 1;i<=size;i++){
                if(carr[i].r() > carr[i-1].r()){
                    rMax= carr[i].r();
                }}
                cout << "\nThe largest Red Value in the array is: " << rMax;

        }
};
//the abstract class

class Shape: public Colour{

    protected:
    static int shapesCreated;
    static int shapesDestroyed;
    protected:
    int shapeID;




    public:

    Shape(double a,double b,double c):Colour(a,b,c){
        setCreateDestroy(); //used to initialize created & destroyed values
        shapesCreated++;
        shapeIDCounter++;
        shapeID = shapeIDCounter;
    }

    void setCreateDestroy(){
        if(createDestroyCounter == 0){
        shapesCreated = 0;
        shapesDestroyed = 0;
        createDestroyCounter = 1;
    }
    }

    virtual string info()=0; //making the class abstract

    ~Shape(){
    shapesDestroyed++;
    }

    static int shapesCount(){
    int shapesAlive = shapesCreated - shapesDestroyed;
    return shapesAlive;

    }

    int id(){
    return shapeID;
    }
};



class Rectangle: public Shape{

    private:
    double x1,y1,x2,y2; //co-ordinates of opposite corners

    public:

    Rectangle(double a,double b,double c,double x_1,double y_1,double x_2,double y_2):Shape(a,b,c){
    x1 = x_1;
    x2 = x_2;
    y1 = y_1;
    y2 = y_2;
    }

    string info(){
    //needs to return the coord's & colour AND SHAPE ID

        string rectInfo = toString();
        rectInfo += "\nThe co-ordinates of the rectangle's opposite corners are (";
        ostringstream convertX1;
        convertX1 << x1;
        rectInfo += ",";
        ostringstream convertY1;
        convertY1 << y1;
        rectInfo += ") and (";
        ostringstream convertX2;
        convertX2 << x2;
        rectInfo += ",";
        ostringstream convertY2;
        convertY2 << y2;
        rectInfo += ")\nThe Shape ID is: \a";
        ostringstream convertID;
        convertID << shapeID;
    return rectInfo;
    }

};

class Circle: public Shape{

    private:
    double x1,y1,radius; //all relevant coords for circle

    public:

    Circle(double a,double b,double c,double x_1,double y_1,double rad):Shape(a,b,c){
    x1 = x_1;
    y1 = y_1;
    radius = rad;
    cout << "test";
    }

    string info(){
    string circInfo = toString();
    circInfo += "\nThe co-ordinates of the circles center is (";
    ostringstream convertX1;
    convertX1 << x1;
    circInfo += ",";
    ostringstream convertY1;
    convertY1 << y1;
    circInfo += ")\nThe radius of the circle is: ";
    ostringstream convertRadius;
    convertRadius << radius;
    circInfo += "\nThe Shape ID is: \a";
    ostringstream convertID;
    convertID << shapeID;
    return circInfo;
    }
};


int main()
{
Circle c1(1,1,1,1,1,1);
return 0;
}

问题：

尝试从派生的形状类创建Rectangle或Circle对象。问题要求shapesDestroyed和Created变量是Shape类中的私有数据成员。但是，尝试在我的派生类构造函数中访问这些是一个问题。基本上它们会随着形状的创建而增加，并且会被破坏。但是，它遇到了我的类中创建和销毁的变量的问题。我已经尝试将这些更改为受保护（问题说明私有）但无济于事。在试图让它正确运行时，我们将非常感谢任何帮助。

Answer 1

作为类成员的静态变量需要在类之外初始化，如下所示：

int Shape::shapesCreated = 0;

在.cpp文件中执行此操作。

我认为即使你可以直接在课堂内进行整理，但我上面应该可以。

C ++未定义对已继承的受保护类成员的引用

1 个答案: