实验1 类和对象（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(6,7);
    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(13, 4, 6);
    c1.show_time();
    
    c1 = reset();
    c1.show_time();
    
    Clock c2(c1);
    c2.set_time(6);
    c2.show_time();
}

#include<iostream>
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}{
    std::cout<<"default constructor called.\n";
}
X::~X(){
    std::cout<<"destructor called.\n";
}
X::X(int m):data{m}{
    std::cout << "constructor called.\n";
}
X::X(const X&obj):data{obj.data}{
    std::cout << "copy constructor called.\n";
}
X::X(X&& obj) noexcept:data{obj.data}{
    std::cout << "copy constructor called.\n";
}
void X::show() const{
    std::cout << data<<std::endl;
}
int main()
{
    X x1;
    x1.show();
    
    X x2{2049};
    x2.show();
    
    X x3{x1};
    x3.show();
    
    X x4{std::move(x2)};
    x4.show();
}

X x1;
x1.show();默认构造函数被编译器自动调用

X x2{2049};
x2.show();构造函数被编译器自动调用

X x3{x1};
x3.show();复制构造函数被编译器调用

X x4{std::move(x2)};移动构造函数被编译器调用
x4.show();

#include <iostream>
#include <iomanip>

class Rectangle
{
    public:
        Rectangle();
        Rectangle(int l,int w);
        Rectangle(const Rectangle &x);
        double len ();
        double wide();
        double area();
        double circumference();
        void resize(double times);
        void resize(double l_times,  double l_);
        
        ~Rectangle()=default;
    private:
        double lenth,width;
}; 
Rectangle::Rectangle()
{
    lenth=2.0;
    width=1.0;
}
Rectangle::Rectangle(int l,int w)
{
    lenth=l;
    width=w;
}
Rectangle::Rectangle(const Rectangle &x)
{
    lenth=x.lenth;
    width=x.width;
}
double Rectangle::len()
{
    return lenth;
}
double Rectangle::wide()
{
    return width;
}
double Rectangle::area()
{
    return (lenth*width);
}
double Rectangle::circumference()
{
    return (lenth+width)*2;
    
}
void Rectangle::resize(double times){
    lenth*=times;
    width*=times;
}
void Rectangle::resize(double l_times,double w_times)
{
    lenth*=l_times;
    width*=w_times;
}
void output(const Rectangle &rect) 
{
using namespace std;
Rectangle a=rect;
cout << "矩形信息: \n";
cout << fixed << setprecision(2); 
cout <<std::left<<setw(8) << "长：  " << left << a.len() << endl;
cout <<std::left<<setw(8) << "宽：  " << left << a.wide() << endl;
cout <<std::left<<setw(8) << "面积：  " << left<< a.area() << endl;
cout <<std::left<<setw(8) << "周长：  " << left << a.circumference() << endl;
cout << 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);
}