实验1 类和对象（1）

实验任务二

1.源码

#include<iostream>
using namespace std;

class Point {
public:
    Point(int x0 =0, int y0 =0) ;
    Point(const Point& p);
    ~Point() = default;

    int get_x()const { return x; }
    int get_y()const { return y; }
    void show() const;

private:
    int x , y;

};
Point::Point(int x0, int y0) :x{ x0 }, y{ y0 } { cout << "constructor called" << endl; }
Point::Point(const Point& p) : x{ p.x }, y{ p.y } { cout << "Copy constructor called" << endl; }
void Point::show() const {
    cout << "( " << x << " , " << y << " )" << endl;
}
int main() {
    Point p1 (4,5);
    p1.show();

    Point p2 = p1;
    p2.show();

    Point p3{ p2 };
    p3.show();
    cout << p3.get_x() << endl;
}

 

实验任务三

源码

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

class Clock {
public:
    Clock(int h = 0, int m = 0, int s = 0);
    Clock(const Clock& t);
    ~Clock()=default;
    void setTime(int h, int m = 0, int s = 0);
    void showTime()const;
private:
    int hour, minute, second;
};

Clock::Clock(int h, int m, int s) :hour(h), minute(m), second(s) { cout << "constructor called" << endl; }
Clock::Clock(const Clock& t) : hour(t.hour), minute(t.minute), second(t.second) { cout << "Copy constructor called" << endl; }

void Clock::setTime(int h, int m, int s) {
    hour = h;
    minute = m;
    second = s;
}
void Clock::showTime() const {
    cout << setfill('0') << setw(2) << hour << ":" << setw(2) << minute << ":" << setw(2) << second << endl;
}

Clock reset() {
    return Clock(0, 0, 0);
}
int main() {
    Clock c1(12, 0, 5);
    c1.showTime();

    c1= reset();
    c1.showTime();

    Clock c2(c1);
    c2.setTime(6);
    c2.showTime();
}

测试截图

实验任务四：

源码

#include<iostream>
using namespace std;

class X {
public:
    X();
    ~X();
    X(int m);
    X(const X& obj);
    X(X&& obj)noexcept;
    void show()const;
private:
    int data;
};

X::X() :data(42) { cout << "default constructor called.\n"; }
X::~X() { cout << "destructor called.\n"; }
X::X(int m) : data(m) { cout << "constructor called.\n"; }
X::X(const X& obj) : data(obj.data) { cout << "copy constructor called.\n"; }
X::X(X&&obj)noexcept:data(obj.data) { cout << "move constructor called.\n"; }
void X::show()const { cout << data << endl; }

int main() {
    X x1;
    x1.show();

    X x2{ 2049 };
    x2.show();

    X x3(x1);
    x3.show();

    X x4(move(x2));
    x4.show();
}

测试截图

分析：

 在执行24行时，默认构造器被调用，调用了16行，在执行27行时，18行含参构造函数被调用，在执行30行时，19行复制构造函数被调用，在执行33行时20行移动构造函数被调用。

 

当程序执行到line35的 } ，析构函数被编译器自动调用，销毁和清理了对象x1、x2、x3、x4占用的资源，运行结果截图中最后4行输出，析构函数在最后程序结束前被调用了。

 

 

实验任务5：

源码

#include<iostream>
#include<iomanip>
using namespace std;
class Rectangle {
public:
    Rectangle(double length = 2.0, double width = 1.0);
    Rectangle(const Rectangle& r);
    ~Rectangle();
    
    double len() { return length; };
    double wide() { return width; };
    double area() { return length*width; };
    double circumference() { return(width + length) * 2; };
    void resize(int m);
    void resize(int m,int n);
    //void output(const Rectangle& rect);

private:
    double length, width;
};

Rectangle::Rectangle(double l, double w) :length(l), width(w) {};
Rectangle::Rectangle(const Rectangle& r) :length(r.length), width(r.width) {};
Rectangle::    ~Rectangle() {};
void Rectangle::resize(int m) { length *= m; width *= m; };
void Rectangle::resize(int m,int n) { length *= m; width *= n; };

void output(Rectangle& rect) {
    cout << "矩形信息: \n";
    cout << fixed << setprecision(2) << "长：    " << rect.len() << endl << "宽：    " << rect.wide()
        << endl << "面积：  " << rect.area() << endl << "周长：  " << rect.circumference() << endl << endl;

}
int main(){
        Rectangle rect1; 
        output(rect1);
        Rectangle rect2(10, 5); 
        output(rect2);
        Rectangle rect3(rect1);
        rect3.resize(2); 
        output(rect3);
        rect3.resize(5, 2); 
        output(rect3);
    }

测试截图