实验1 类和对象（1）

#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(50,30);
p1.show();

Point p2 = p1;
p2.show();

Point p3{p2};
p3.show();
cout << p3.get_x() << endl;
}

 

 

#include <iostream>
#include <iomanip>
using std::cout;
using std::endl;

class Clock {
public:
  Clock(int h = 5, int m = 16, int s = 20);
  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(18, 33, 7);   
  c1.show_time();
  c1 = reset();    
  c1.show_time();
  Clock c2(c1);  
  c2.set_time(7);
  c2.show_time();
}

 

 

#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();
    
}

 

 line 34调用默认构造函数，line 37调用构造函数，line 40调用复制构造函数，line 43调用移动构造函数；

程序结束时调用析构函数，释放x1，x2，x3，x4，共调用4次。

#include <iostream>
#include <iomanip>
using namespace std;
class Rectangle{
    public:
        Rectangle();
        Rectangle(double l, double w);
        Rectangle(const Rectangle& p);
        ~Rectangle() = default;
        double len() const;
        double wide() const;
        double area() const;
        double circumference() const;
        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& p):length{p.length},width{p.width}{};
double Rectangle::len() const{ return length; }
double Rectangle::wide() const{ return width; }
double Rectangle::area() const{ return length*width; }
double Rectangle::circumference() const{ return 2*(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 << "矩形信息: \n";
  cout << fixed << setprecision(2);      
  cout << "长：   "<< left << rect.len() <<endl
       << "宽：   "<< left << rect.wide() <<endl
       << "面积： "<< left << rect.area() <<endl
       << "周长： "<< left << rect.circumference() <<endl
       << endl;
  
}
int main() {
  Rectangle rect1;     // 默认构造函数被调用
  output(rect1);
  Rectangle rect2(10, 5);   // 带有两个参数的构造函数被调用
  output(rect2);
  Rectangle rect3(rect1);   // 复制构造函数被调用
  rect3.resize(2);       // 矩形rect3的长和宽同时缩放2倍
  output(rect3);
  rect3.resize(5, 2);     // 矩形rect3的长缩放5倍, 宽缩放2倍
  output(rect3);
}