实验一：类和对象

实验任务2

#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(19,89);
    p1.show();
    Point p2=p1;
    p2.show();
    Point p3{p2};
    p3.show();
    cout<<p3.get_x()<<endl;
}

实验任务3

#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(9,8,29);
    c1.show_time();
    
    c1=reset();
    c1.show_time();
    
    Clock c2(c1);
    c2.set_time(8,8,8);
    c2.show_time();
}

 

 实验任务4

#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();
}

 

 分析：

X x1，调用默认构造函数，

X x2{2049}，调用带参数的构造函数，

X x3{x1}，调用复制构造函数，

X x4{std::move(x2)}，调用移动构造函数。

析构函数是在程序即将结束之前被调用的，并且对x1，x2，x3，x4进行销毁。

实验任务5

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