实验一

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(4, 5);  
  p1.show();
  Point p2 = p1;   
  p2.show();
  Point p3{p2};    
  p3.show();
  cout << p3.get_x() << endl;
}

 

运行结果：

修改数据后运行结果

 

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(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：

更改数据后运行结果：

 

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();
}

 

运行结果：

分析：

line39调用默认构造函数；line41调用构造函数；line43调用复制构造函数；line45调用移动构造函数；

line47析构函数被调用了4次，销毁和清理了对象x1、x2、x3、x4占用的资源。

 实验任务5

源代码：

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

 

运行结果：