实验一：类与对象

实践任务2：

#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;
}

运行：

 

 

修改：

运行：

 实践任务3：

#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 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 {
    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.show_time();
    c1 = reset(); 
    c1.show_time();
    Clock c2(c1);
    c2.set_time(6);
    c2.show_time();
}

 运行结果：

 修改：

运行： 

 实践任务4：

#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(); 
}

 

 

运行结果：

 

分析：

X x1;//默认构造函数被调用 

X x2{2049}; //参数构造函数被调用

X x3{x1}; //复制构造函数被调用

X x4{move(x2)};//移动构造函数被调用

析构函数是在程序结束后被调用来销毁x1,x2,x3,x4的。

实践任务5：

#include <iostream> 
#include <iomanip>
using namespace std;
using std::left;
class Rectangle{
    public:
        Rectangle(double l=2.0,double w=1.0);
        ~Rectangle()=default;
        Rectangle(double m);
        Rectangle(const Rectangle& rect);
        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 time){
            length*=time;
            width*=time;
        }
        void resize(int l_times,int w_times ){
            length*=l_times;
            width*=w_times;
        }
    private:
        double length,width;


}; 
Rectangle::Rectangle(double l,double w):length{l},width{w}{
}
Rectangle::Rectangle(const Rectangle& rect):length{rect.length},width{rect.width}{
}
void output(const Rectangle &rect) { 
     cout << "矩形信息: \n"; 
    cout << fixed << setprecision(2);
    cout<<left<<setw(5)<<"长:"<<rect.len()<<endl;
    cout<<left<<setw(5)<<"宽:"<<rect.wide()<<endl;
    cout<<left<<setw(5)<<"面积:"<<rect.area()<<endl;
    cout<<left<<setw(5)<<"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);
}