在下列代码基础上增加或修改如下功能： 1）带默认值或者重载的普通构造函数 2）析构函数（增加一条输出语句做测试即可） 3）将3个立方柱定义成对象数组并初始化 4）this指针请显示使用 #include <iostream> using namespace std; class cube//定义类 { public: //构造函数重载或者带默认值，建议二选一，允许对象传参和不传参都可以执行 //析构函数 void setvalue();//输入数据成员值 float volume();//计算体积 private: float length;//长、宽、高数据成员，定义成私有数据 float width; float height; }; void cube::setvalue()//显示使用this指针 { cout<<"请输入长方柱的长、宽、高"<<endl; cin>>length>>width>>height; } float cube::volume()//类外定义函数，请显示使用this指针 { return length*width*height; } int main() { cube c1,c2,c3;//修改成对象数组并初始化 c1.setvalue(); cout<<"该长方柱的体积为："<<c1.volume()<<""<<endl; c2.setvalue(); cout<<"该长方柱的体积为："<<c2.volume()<<""<<endl; c3.setvalue(); cout<<"该长方柱的体积为："<<c3.volume()<<""<<endl; return 0; }

1）在代码中增加如下带默认值的普通构造函数：

Cuboid() : length(1), width(1), height(1) {}

2）在代码中增加如下析构函数并加入一条输出语句做测试：

~Cuboid() {cout << "Cuboid destroyed" << endl;}

3）将3个立方柱定义成对象数组并初始化，修改后的代码如下：

#include <iostream>
using namespace std;

class Cuboid {
public:
    Cuboid() : length(1), width(1), height(1) {}
    Cuboid(double l, double w, double h) : length(l), width(w), height(h) {}
    ~Cuboid() {cout << "Cuboid destroyed" << endl;}
    double volume() {return length * width * height;}
    double surfaceArea() {return 2 * (length * width + width * height + height * length);}
private:
    double length, width, height;
};

int main() {
    Cuboid c[3] = {Cuboid(1, 2, 3), Cuboid(4, 5, 6), Cuboid(7, 8, 9)};
    for (int i = 0; i < 3; i++) {
        cout << "Cuboid " << i+1 << " volume: " << c[i].volume() << endl;
        cout << "Cuboid " << i+1 << " surface area: " << c[i].surfaceArea() << endl;
    }
    return 0;
}

4）在代码中加入this指针并显示使用，修改后的代码如下：

#include <iostream>
using namespace std;

class Cuboid {
public:
    Cuboid() : length(1), width(1), height(1) {}
    Cuboid(double l, double w, double h) : length(l), width(w), height(h) {}
    ~Cuboid() {cout << "Cuboid destroyed" << endl;}
    double volume() {return this->length * this->width * this->height;}
    double surfaceArea() {return 2 * (this->length * this->width + this->width * this->height + this->height * this->length);}
private:
    double length, width, height;
};

int main() {
    Cuboid c[3] = {Cuboid(1, 2, 3), Cuboid(4, 5, 6), Cuboid(7, 8, 9)};
    for (int i = 0; i < 3; i++) {
        cout << "Cuboid " << i+1 << " volume: " << c[i].volume() << endl;
        cout << "Cuboid " << i+1 << " surface area: " << c[i].surfaceArea() << endl;
    }
    return 0;
}