实验1 类与对象（1）

实验任务2源代码：

#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(44,55);
    p1.show() ;
    
    Point p2=p1;
    p2.show();
    
    Point p3{p2};
    p3.show();
    cout<<p3.get_x()<<endl; 
} 

实验任务3源代码：

#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(10,20,4);
    c1.show_time();
    
    c1=reset();
    c1.show_time();
    
    Clock c2(c1);
    c2.set_time(8);
    c2.show_time();
}

实验任务4源代码：

#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<<"move 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();
}

问题分析：1.line42——X（）默认构造函数，line45——X（int m）构造函数，line48——x(const X& obj)复制构造函数，line51——X（X&& obj）移动构造函数，line43、46、49、52——show（）。2.析构函数的调用顺序为依次销毁和清理了x4、x3、x2、x1的所占资源。

#include<iostream>
#include<iomanip>
class Rectangle
{
    public:
        Rectangle()=default;
        Rectangle(float l,float w);
        Rectangle(const Rectangle& R);
        ~Rectangle()=default;
        float len() const {return length;}
        float wide() const {return width;}
        float area() const {return (length*width);}
        float circumference() const {return (2*length+2*width);}
        float resize(int times) ;
        float resize(int l_times,int w_times) ;
    private:
        float length=2.0,width=1.0;
};

Rectangle::Rectangle(float l,float w)
{
    length=l; width=w;
}
Rectangle::Rectangle(const Rectangle& R)
{
    length=R.length; width=R.width;
}

float Rectangle::resize(int times)
{
    length*=times;
    width*=times;
}
float 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<<"长:    "<<rect.len()<<endl;
    cout<<"宽:    "<<rect.wide()<<endl;
    cout<<"面积:  "<<rect.area()<<endl;
    cout<<"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);
}