实验1 类和对象

实验任务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(7, 8); 
    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 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 construct 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(17, 12, 5); 
    c1.show_time();
    
    c1 = reset(); 
    c1.show_time();
    
    Clock c2(c1);
    c2.set_time(8);
    c2.show_time();
}

实验任务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(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{ std::move(x2) };
    x4.show();
}

X::~X() {
    cout << "destructor called.\n";
}

X x1; 执行时默认构造函数被调用；

X x2{2049}; 执行时构造函数被调用；

X x3{x1}; 执行时复制构造函数被调用；

X x4{ std::move(x2) }; 执行时移动构造函数被调用；

每个对象在使用完后都会调用一次析构函数；

实验任务5

#include <iostream> 
#include <iomanip>
using namespace std;

class Rectangle{
public:
    Rectangle():length(2.0),width(1.0){    };
    Rectangle(double l,double w):length(l),width(w){ };
    Rectangle(const Rectangle &rec):length(rec.length),width(rec.width){ };
    ~Rectangle()=default;
    
    double len() const {return length;}
    double wide() const {return width;}
    double area() const {return length*width;}
    double circumference() const {return 2*(length+width);}
    
    void resize(double times){
        length*=times;
        width*=times;
    }
    
    void resize(double l_times,double w_times){
        length*=l_times;
        width*=w_times;
    }
        
private:
    double length;
    double width;
        
};

void output(const Rectangle &rect) { 
    cout << "矩形信息: \n"; 
    cout << fixed << setprecision(2);
    cout<<"长:"<<"\t"<<rect.len()<<endl; 
    cout<<"宽:"<<"\t"<<rect.wide()<<endl; 
    cout<<"面积:"<<"\t"<<rect.area()<<endl; 
    cout<<"周长:"<<"\t"<<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);
}