实验1

#include<iostream>
using std::cout;
using std::endl;

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(7, 8);
    p1.show();
    
    Point p2 = p1;
    p2.show();
    
    Point p3{p2};
    p3.show();
    cout << p3.get_x() << endl;
}

#include<iostream>
#include<iomanip>
using std::cout;
using std::endl;

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

void Clock::show_time() const {
    using std::setw;
    using std::setfill;
    cout << setfill('0') <<setw(2) << hour << ":"
         << setw(2) << minute << ":"
         << setw(2) << second << endl;
}

Clock reset() {
    return Clock(0, 0, 0);
}

int main()
{
    Clock c1(11, 1, 6);
    c1.show_time();
    
    c1 = reset();
    c1.show_time();
    
    Clock c2{c1};
    c2.set_time(7);
    c2.show_time();
}

#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();
}

 

line 42调用默认构造函数，line 45调用带参数的构造函数，line 48 调用复制构造函数
line 51 调用移动构造函数，当对象被删除时调用析构函数，顺序依次为 x3, x2, x1

 

#include <iostream>
#include <iomanip>
using namespace std;
// 矩形类Rectangle的定义和实现
// 补足代码
// ×××
class Rectangle{
    private:
        float length; //矩形的长度
        float width; //矩形的宽度
    
    public:
        Rectangle();
        Rectangle(float l, float w);
        Rectangle(const Rectangle& rect);
        ~Rectangle();
        float len() const;
        float wide() const ;
        float area() const ;
        float circumference() const ;
        void resize(float times);
        void resize(float l_times, float w_times); 
};

Rectangle::Rectangle(): length{2.0}, width{1.0} {}

Rectangle::Rectangle(float l, float w): length{l}, width{w} {}

Rectangle::Rectangle(const Rectangle& rect): length{rect.length}, width{rect.width} {
} 

Rectangle::~Rectangle() {}

float Rectangle::len() const {
    return length;
}

float Rectangle::wide() const {
    return width;
}

float Rectangle::area() const {
    return length * width;
}

float Rectangle::circumference() const {
    return 2 * (length + width);
}

void Rectangle::resize(float times) {
    length *= times;
    width *= times;
}

void Rectangle::resize(float ltimes, float wtimes) {
    length *= ltimes;
    width *= wtimes;
}
// 普通函数, 用于输出矩形信息
void output(const Rectangle& rect) {
  using namespace std;
  cout << "矩形信息: \n";
  cout << fixed << setprecision(2);// 控制输出格式：以浮点数形式输出、小数部分保留两位
  // 补足代码：分行输出矩形长、宽、面积、周长
  // ×××
  cout <<"长：  " << left << setw(6) << rect.len() << endl;
  cout <<"宽：  " << left << setw(6) << rect.wide() << endl;
  cout <<"面积：" << left << setw(6) << rect.area() << endl;
  cout <<"周长：" << left << setw(6) << rect.circumference() << endl;
  cout<<endl; 
}
// 主函数，测试Rectangle类
int main() {
  Rectangle rect1; // 默认构造函数被调用
  output(rect1);
  Rectangle rect2(10, 5); // 带有两个参数的构造函数被调用
  output(rect2);
  Rectangle rect3(rect1); // 复制构造函数被调用
  rect3.resize(2); // 矩形rect3的长和宽同时缩放2倍
  output(rect3);
  rect3.resize(5, 2); // 矩形rect3的长缩放5倍, 宽缩放2倍
  output(rect3);
}

我通过这次的实验理解了：

类、对象的基础理解，知道了什么是类的抽象、封装，类的接口

如何用C++正确定义、实现、测试类

如何用C++正确创建对象，并基于对象编程

如何对C++内存资源管理技术的初步了解，知道构造函数、析构函数的用途和调用时机