实验1 类和对象(1)

实验任务2

#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;
}

 

 

 

 

 

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 << ":" << 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();
    
    return 0;
}

 

 

 

 

 

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();
    
    return 0;
}

 

 

在43行时，x1，调用默认构造函数 X()

在46行时，x2，调用含参数的构造函数 X(int m)

在49行时，x3，调用复制构造函数 X(const X & obj)

在52行时，x4，调用移动构造函数 X(X && obj)

主函数结束前，x1,x2,x3,x4, 都调用了析构函数 ~X()

 

实验任务5

#include<iostream>
#include<iomanip>

class Rectangle{
public:

Rectangle();
Rectangle(double c, double k);
Rectangle(const Rectangle & obj);
void resize(double l_times, double w_times);
void resize(double times);
double len() const ;
double wide() const ;
double area() const ;
double circumference() const ;

private:

double length, width;

};

Rectangle::Rectangle(){
length = 2;
width = 1;
}

Rectangle::Rectangle(double len, double wide){
length = len;
width = wide;
}

Rectangle::Rectangle(const Rectangle & obj) : length{obj.length}, width{obj.width}{}

void Rectangle::resize(double l_times, double w_times){
length *= l_times;
width *= w_times;
}

void Rectangle::resize(double times){
length *= times;
width *= times;
}

double Rectangle::circumference() const{
return (length + width) * 2;
}

double Rectangle::area() const {
return length * width;
}

double Rectangle::len()const {
return length;
}

double Rectangle::wide()const {
return width;
}

void output(const Rectangle & rect){

using namespace std;

cout << "矩阵信息：\n";
cout << fixed << setprecision(2);

cout << "长： " << rect.len() << endl;
cout << "宽： " << rect.wide() << endl;
cout << "面积： " << rect.area() << endl;
cout << "周长： " << 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);

}

 

 

 

实验总结：
一些收获：

1.一个const对象不能调用它的non-const成员函数，只能使用const成员。半天过不了编译，百度的结果

2.虽然"private:"的函数外部不能访问，但是我们可以写"public:"来访问它