实验1 类和对象（1）

实验任务二

1.源码

 1 #include<iostream>
 2 using namespace std;
 3 
 4 class Point {
 5 public:
 6     Point(int x0 =0, int y0 =0) ;
 7     Point(const Point& p);
 8     ~Point() = default;
 9 
10     int get_x()const { return x; }
11     int get_y()const { return y; }
12     void show() const;
13 
14 private:
15     int x , y;
16 
17 };
18 Point::Point(int x0, int y0) :x{ x0 }, y{ y0 } { cout << "constructor called" << endl; }
19 Point::Point(const Point& p) : x{ p.x }, y{ p.y } { cout << "Copy constructor called" << endl; }
20 void Point::show() const {
21     cout << "( " << x << " , " << y << " )" << endl;
22 }
23 int main() {
24     Point p1 (4,5);
25     p1.show();
26 
27     Point p2 = p1;
28     p2.show();
29 
30     Point p3{ p2 };
31     p3.show();
32     cout << p3.get_x() << endl;
33 }

实验任务三

源码

#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 setTime(int h, int m = 0, int s = 0);
    void showTime()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::setTime(int h, int m, int s) {
    hour = h;
    minute = m;
    second = s;
}
void Clock::showTime() 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.showTime();

    c1= reset();
    c1.showTime();

    Clock c2(c1);
    c2.setTime(6);
    c2.showTime();
}

测试截图

实验任务四：

源码

 1 #include<iostream>
 2 using namespace std;
 3 
 4 class X {
 5 public:
 6     X();
 7     ~X();
 8     X(int m);
 9     X(const X& obj);
10     X(X&& obj)noexcept;
11     void show()const;
12 private:
13     int data;
14 };
15 
16 X::X() :data(42) { cout << "default constructor called.\n"; }
17 X::~X() { cout << "destructor called.\n"; }
18 X::X(int m) : data(m) { cout << "constructor called.\n"; }
19 X::X(const X& obj) : data(obj.data) { cout << "copy constructor called.\n"; }
20 X::X(X&&obj)noexcept:data(obj.data) { cout << "move constructor called.\n"; }
21 void X::show()const { cout << data << endl; }
22 
23 int main() {
24     X x1;
25     x1.show();
26 
27     X x2{ 2049 };
28     x2.show();
29 
30     X x3(x1);
31     x3.show();
32 
33     X x4(move(x2));
34     x4.show();
35 }

测试截图

分析：

 在执行24行时，默认构造器被调用，调用了16行，在执行27行时，18行含参构造函数被调用，在执行30行时，19行复制构造函数被调用，在执行33行时20行移动构造函数被调用。

当程序执行到line35的 } ，析构函数被编译器自动调用，销毁和清理了对象x1、x2、x3、x4占用的资源，运行结果截图中最后4行输出，析构函数在最后程序结束前被调用了。

实验任务5：

源码

 1 #include<iostream>
 2 #include<iomanip>
 3 using namespace std;
 4 class Rectangle {
 5 public:
 6     Rectangle(double length = 2.0, double width = 1.0);
 7     Rectangle(const Rectangle& r);
 8     ~Rectangle();
 9     
10     double len() { return length; };
11     double wide() { return width; };
12     double area() { return length*width; };
13     double circumference() { return(width + length) * 2; };
14     void resize(int m);
15     void resize(int m,int n);
16     //void output(const Rectangle& rect);
17 
18 private:
19     double length, width;
20 };
21 
22 Rectangle::Rectangle(double l, double w) :length(l), width(w) {};
23 Rectangle::Rectangle(const Rectangle& r) :length(r.length), width(r.width) {};
24 Rectangle::    ~Rectangle() {};
25 void Rectangle::resize(int m) { length *= m; width *= m; };
26 void Rectangle::resize(int m,int n) { length *= m; width *= n; };
27 
28 void output(Rectangle& rect) {
29     cout << "矩形信息: \n";
30     cout << fixed << setprecision(2) << "长：    " << rect.len() << endl << "宽：    " << rect.wide()
31         << endl << "面积：  " << rect.area() << endl << "周长：  " << rect.circumference() << endl << endl;
32 
33 }
34 int main(){
35         Rectangle rect1; 
36         output(rect1);
37         Rectangle rect2(10, 5); 
38         output(rect2);
39         Rectangle rect3(rect1);
40         rect3.resize(2); 
41         output(rect3);
42         rect3.resize(5, 2); 
43         output(rect3);
44     }

测试截图