实验1 类和对象

实验任务2
#include <iostream>
#include <vector>

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(4, 7); 
    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 << ":";
    cout << setw(2) << minute << ":";
    cout << setw(2) << second << endl;
}

Clock reset() {
    return Clock(0, 0, 0); 
}

int main()
{
    Clock c1(11, 0, 4); 
    c1.show_time();
    
    c1 = reset(); 
    c1.show_time();
    
    Clock c2(c1); 
    c2.set_time(4);
    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<<"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();
 }

47.48行，默认构造函数X()被调用；
50.51行，构造函数X(int m)被调用；
53.54行，复制构造函数X(const X& obj)被调用；
56.57行，移动构造函数X(X&& obj) noexcept被调用。
在对象生命周期结束时，析构函数被调用，跟构造函数的调用顺序相反。

实验任务5
#include <iostream>
#include <iomanip>

using namespace std;

class Rectangle
{
  public:
    Rectangle(float l = 2.0,float w = 1.0) : length{l},width{w} {}
    Rectangle(const Rectangle &obj):
    length{obj.length},width{obj.width}{}
            ~Rectangle()=default;
             
    float len() const {return length;}
    float wide() const {return width;}
    float area() const {return length*width;}
    float circumference() const {return 2*(length+width);}
    
    
    void resize(int times);
    void resize(int l_times,int w_times);
    
    private :
    float 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<<"矩阵信息:\n";
    cout<<std::left<<setw(7)<<"长:"<<std::right<<
        fixed<<setprecision(2)<<setw(5)<<rect.len()<<endl;
    cout<<std::left<<setw(7)<<"宽:"<<std::right<<
        fixed<<setprecision(2)<<setw(5)<<rect.wide()<<endl;
    cout<<std::left<<setw(7)<<"面积:"<<std::right<<
        fixed<<setprecision(2)<<setw(5)<<rect.area()<<endl;
    cout<<std::left<<setw(7)<<"周长:"<<std::right<<
        fixed<<setprecision(2)<<setw(5)<<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);
}