实验2

实验2

实验任务一 :

代码组织：

T.h 内容：类T的声明、友元函数声明

T.cpp 内容：类T的实现、友元函数实现

task1.cpp 内容：测试模块、main函数

T.h:

#include <string>

// 类T: 声明
class T {
// 对象属性、方法
public:
    T(int x = 0, int y = 0);   // 普通构造函数
    T(const T &t);  // 复制构造函数
    T(T &&t);       // 移动构造函数
    ~T();           // 析构函数

    void adjust(int ratio);      // 按系数成倍调整数据
    void display() const;           // 以(m1, m2)形式显示T类对象信息

private:
    int m1, m2;

// 类属性、方法
public:
    static int get_cnt();          // 显示当前T类对象总数

public:
    static const std::string doc;       // 类T的描述信息
    static const int max_cnt;           // 类T对象上限

private:
    static int cnt;         // 当前T类对象数目

// 类T友元函数声明
    friend void func();
};

// 普通函数声明
void func();

T.cpp:

#include "T.h"
#include <iostream>
#include <string>

// 类T实现

// static成员数据类外初始化
const std::string T::doc{"a simple class sample"};
const int T::max_cnt = 999;
int T::cnt = 0;

// 类方法
int T::get_cnt() {
   return cnt;
}

// 对象方法
T::T(int x, int y): m1{x}, m2{y} { 
    ++cnt; 
    std::cout << "T constructor called.\n";
} 

T::T(const T &t): m1{t.m1}, m2{t.m2} {
    ++cnt;
    std::cout << "T copy constructor called.\n";
}

T::T(T &&t): m1{t.m1}, m2{t.m2} {
    ++cnt;
    std::cout << "T move constructor called.\n";
}    

T::~T() {
    --cnt;
    std::cout << "T destructor called.\n";
}           

void T::adjust(int ratio) {
    m1 *= ratio;
    m2 *= ratio;
}    

void T::display() const {
    std::cout << "(" << m1 << ", " << m2 << ")" ;
}     

// 普通函数实现
void func() {
    T t5(42);
    t5.m2 = 2049;
    std::cout << "t5 = "; t5.display(); std::cout << '\n';
    std::cout << "func: T objects'current count: " << T::get_cnt() << std::endl;
}

task1.cpp:

#include "T.h"
#include <iostream>

void test_T();

int main() {
    std::cout << "test Class T: \n";
    test_T();

    std::cout << "\ntest friend func: \n";
    func();
}

void test_T() {
    using std::cout;
    using std::endl;

    cout << "T info: " << T::doc << endl;
    cout << "T objects'max count: " << T::max_cnt << endl;
    cout << "T objects'current count: " << T::get_cnt() << endl << endl;

    T t1;
    cout << "t1 = "; t1.display(); cout << endl;

    T t2(3, 4);
    cout << "t2 = "; t2.display(); cout << endl;

    T t3(t2);
    t3.adjust(2);
    cout << "t3 = "; t3.display(); cout << endl;

    T t4(std::move(t2));
    cout << "t4 = "; t4.display(); cout << endl;

    cout << "test: T objects'current count: " << T::get_cnt() << endl;
}

运行截图:

问题1

无法编译，缺少函数声明，友元声明不能作为函数声明

问题2

普通构造函数，在构造时没有传参或按默认参数规则传参时使用
复制构造函数，使用对象来创建新对象， 在使用左值对象传参时使用
移动构造函数，复用原有对象的空间，在使用右值对象传参时使用
析构函数，处理类对象的资源，在对象被销毁或显示调用时使用

问题3

无法编译，因为该函数为静态函数，只接受一次初始化。

实验任务2

Complex.h:

#ifndef MY_COMPLEX_H_
#define MY_COMPLEX_H_

#include <string>

class Complex
{
    // 对象属性、方法
    private:
        double real, imag;
        
    public:
        Complex(double r = 0.0, double i = 0.0);    // 普通构造函数
        Complex(const Complex&);    // 复制构造函数
        Complex(const Complex&&) noexcept;    // 移动构造函数

        double get_real() const;    // 显示Complex类对象实部
        double get_imag() const;    // 显示Complex类对象虚部
        Complex& operator=(const Complex&);
        Complex& operator=(const Complex&&) noexcept;    // 重载=运算符
        void add(const Complex&);    // 将一个Complex类对象加到另一个Complex类对象上
    // 类属性、方法
    public:
        static const std::string doc;    // 用于类说明
        
    // 类Complex友元函数声明
    friend void output(const Complex&);    // 以a+bi的形式显示Complex类对象的信息
    friend double abs(const Complex&);    // 对Complex类对象取模
    friend Complex add(const Complex&, const Complex&);    // 实现两个Complex类对象相加，返回Complex类对象
    friend bool is_equal(const Complex&, const Complex&);    // 判断两个Complex类对象是否相等
    friend bool is_not_equal(const Complex&, const Complex&);    //    判断两个Complex类对象是否相等
};

void output(const Complex&);
double abs(const Complex&);
Complex add(const Complex&, const Complex&);
bool is_equal(const Complex&, const Complex&);
bool is_not_equal(const Complex&, const Complex&);
        
#endif

Complex.cpp:

#include "Complex.h"

#include <iostream>
#include <utility>
#include <string>
#include <cmath>

const std::string Complex::doc = "a smplified complex class";

Complex::Complex(double r, double i): real(r), imag(i){}

Complex::Complex(const Complex &c): real(c.real), imag(c.imag){}

Complex::Complex(const Complex &&c) noexcept : real(c.real), imag(c.imag){}

Complex& Complex::operator=(const Complex &c)
{
    if (this != &c)
    {
        real = c.real;
        imag = c.imag;    
    }
    return *this;    
}

Complex& Complex::operator=(const Complex &&c) noexcept
{
    if (this != &c)
    {
        real = c.real;
        imag = c.imag;    
    }
    return *this;
}

double Complex::get_real() const{
    return real;
}

double Complex::get_imag() const{
    return imag;
}

void Complex::add(const Complex &c){
    real += c.real;
    imag += c.imag;
}

void output(const Complex &c){
    std::cout   << c.get_real() 
                << (c.get_imag() < 0 ? " - " : " + ") 
                << std::abs(c.get_imag()) << 'i';
}
        
double abs(const Complex &c){
    return std::sqrt(c.get_real() * c.get_real() + c.get_imag() * c.get_imag());
}

Complex add(const Complex &c1, const Complex &c2){
    Complex c;
    c.add(c1);
    c.add(c2);
    return c;
}

bool is_equal(const Complex &c1, const Complex &c2){
    return c1.get_real() == c2.get_real() && c1.get_imag() == c2.get_imag();
}

bool is_not_equal(const Complex &c1, const Complex &c2){
    return !is_equal(c1, c2);
}

task2.cpp:

#include "Complex.h"

#include <iostream>
#include <iomanip>
#include <complex>

void test_Complex();
void test_std_complex();

int main() {
    std::cout << "*******测试1: 自定义类Complex*******\n";
    test_Complex();

    std::cout << "\n*******测试2: 标准库模板类complex*******\n";
    test_std_complex();
}

void test_Complex() {
    using std::cout;
    using std::endl;
    using std::boolalpha;

    cout << "类成员测试: " << endl;
    cout << Complex::doc << endl << endl;

    cout << "Complex对象测试: " << endl;
    Complex c1;
    Complex c2(3, -4);
    Complex c3(c2);
    Complex c4 = c2;
    const Complex c5(3.5);

    cout << "c1 = "; output(c1); cout << endl;
    cout << "c2 = "; output(c2); cout << endl;
    cout << "c3 = "; output(c3); cout << endl;
    cout << "c4 = "; output(c4); cout << endl;
    cout << "c5.real = " << c5.get_real() 
         << ", c5.imag = " << c5.get_imag() << endl << endl;

    cout << "复数运算测试: " << endl;
    cout << "abs(c2) = " << abs(c2) << endl;
    c1.add(c2);
    cout << "c1 += c2, c1 = "; output(c1); cout << endl;
    cout << boolalpha;
    cout << "c1 == c2 : " << is_equal(c1, c2) << endl;
    cout << "c1 != c2 : " << is_not_equal(c1, c2) << endl;
    c4 = add(c2, c3);
    cout << "c4 = c2 + c3, c4 = "; output(c4); cout << endl;
}

void test_std_complex() {
    using std::cout;
    using std::endl;
    using std::boolalpha;

    cout << "std::complex<double>对象测试: " << endl;
    std::complex<double> c1;
    std::complex<double> c2(3, -4);
    std::complex<double> c3(c2);
    std::complex<double> c4 = c2;
    const std::complex<double> c5(3.5);

    cout << "c1 = " << c1 << endl;
    cout << "c2 = " << c2 << endl;
    cout << "c3 = " << c3 << endl;
    cout << "c4 = " << c4 << endl;

    cout << "c5.real = " << c5.real() 
         << ", c5.imag = " << c5.imag() << endl << endl;

    cout << "复数运算测试: " << endl;
    cout << "abs(c2) = " << abs(c2) << endl;
    c1 += c2;
    cout << "c1 += c2, c1 = " << c1 << endl;
    cout << boolalpha;
    cout << "c1 == c2 : " << (c1 == c2)<< endl;
    cout << "c1 != c2 : " << (c1 != c2) << endl;
    c4 = c2 + c3;
    cout << "c4 = c2 + c3, c4 = " << c4 << endl;
}

运行截图:

问题

1. 标准库更简洁，运算本身就是一种函数
2. 没有必要，因为这些函数可以通过get函数获取值
没有，他是采用特化的方式
需要打破封装，无法通过接口处理类内成员时使用友元
3. 类无法使用=, 所以需要提供一个方法来替代=以接受传入的对象。

实验任务3:

### PlayerControl.h:
#pragma once
#include <string>

enum class ControlType {Play, Pause, Next, Prev, Stop, Unknown};

class PlayerControl {
public:
    PlayerControl();

    ControlType parse(const std::string& control_str);   // 实现std::string --> ControlType转换
    void execute(ControlType cmd) const;   // 执行控制操作（以打印输出模拟）       

    static int get_cnt();

private:
    static int total_cnt;   
};

PlayerControl.cpp:

#include "PlayerControl.h"
#include <iostream>
#include <algorithm>   

int PlayerControl::total_cnt = 0;

PlayerControl::PlayerControl() {}

ControlType PlayerControl::parse(const std::string& control_str) {
    std::string trans_result;
    for (auto &c : control_str)
        trans_result += std::tolower(c);
    ++total_cnt;
    if ("play" == trans_result)
        return ControlType::Play;
    else if ("next" == trans_result)
        return ControlType::Next;
    else if ("prev" == trans_result)
        return ControlType::Prev;
    else if ("stop" == trans_result)
        return ControlType::Stop;
    else if ("pause" == trans_result)
        return ControlType::Pause;
    else
        return ControlType::Unknown;
}

void PlayerControl::execute(ControlType cmd) const {
    switch (cmd) {
    case ControlType::Play:  std::cout << "[play] Playing music...\n"; break;
    case ControlType::Pause: std::cout << "[Pause] Music paused\n";    break;
    case ControlType::Next:  std::cout << "[Next] Skipping to next track\n"; break;
    case ControlType::Prev:  std::cout << "[Prev] Back to previous track\n"; break;
    case ControlType::Stop:  std::cout << "[Stop] Music stopped\n"; break;
    default:                 std::cout << "[Error] unknown control\n"; break;
    }
}

int PlayerControl::get_cnt() {
    return total_cnt;
}

task3.cpp:

#include "PlayerControl.h"
#include <iostream>

void test() {
    PlayerControl controller;
    std::string control_str;
    std::cout << "Enter Control: (play/pause/next/prev/stop/quit):\n";

    while(std::cin >> control_str) {
        if(control_str == "quit")
            break;
        
        ControlType cmd = controller.parse(control_str);
        controller.execute(cmd);
        std::cout << "Current Player control: " << PlayerControl::get_cnt() << "\n\n";
    }
}

int main() {
    test();
}

运行截图:

实验任务4:

Fraction.h:

#ifndef FRACTION_H_
#define FRACTION_H_

#include <string>


                
    class Fraction
    {
        public:
            Fraction(int u = 0, int d = 1);    
            Fraction(Fraction&);   
            Fraction(Fraction&&) noexcept;    
            
            int get_up() const;    
            int get_down() const;    
            Fraction negative() const;    
            
        private:
            int up, down;
            
            void simplify();   
        
        public:
            static const std::string doc;

                // 工具函数
            static      void output(const Fraction&);    
            static    Fraction add(const Fraction&, const Fraction&);    
            static    Fraction sub(const Fraction&, const Fraction&);   
            static    Fraction mul(const Fraction&, const Fraction&);    
            static    Fraction div(const Fraction&, const Fraction&);    
            
    };

    

#endif

Fraction.cpp:

#include "Fraction.h"

#include <iostream>
#include <cmath>
#include <string>
#include <numeric>

    
    const std::string Fraction::doc = "Fraction类 v 0.01版.\n目前仅支持分数对象的构造、输出、加/减/乘/除运算.";
    
    Fraction::Fraction(int u, int d): up(u), down(d)
    {
        simplify();
    }
    
    Fraction::Fraction(Fraction &f): up(f.up), down(f.down)
    {
        simplify();
    }
    
    int Fraction::get_up() const
    {
        return up;
    }
    
    int Fraction::get_down() const
    {
        return down;
    }
    
    Fraction Fraction::negative() const
    {
        return Fraction(-this->up,this->down);
    }
    
    void Fraction::simplify()
    {
        if (up == 0) {
            down = 1;
            return;
        }

        if (down < 0) {
            up = -up;
            down = -down;
        }
        int g = std::gcd(std::abs(up), std::abs(down));
        if (g > 1) {
            up /= g;
            down /= g;
        }
    }
    
    void output(const Fraction &f)
    {
        std::cout << f.get_up() << "/" << f.get_down() << std::endl;
    }
    
    Fraction add(const Fraction &f1, const Fraction &f2)
    {
        long long new_up = f1.get_up() * f2.get_down()
                     + f2.get_up() * f1.get_down();
        long long new_down = f1.get_down() * f2.get_down();
        return Fraction(new_up, new_down);
    }
    
    Fraction sub(const Fraction &f1, const Fraction &f2)
    {
        return add(f1, f1.negative());
    }
    
    Fraction mul(const Fraction &f1, const Fraction &f2)
    {
        long long new_up = f1.get_up() * f2.get_up();
        long long new_down = f1.get_down() * f2.get_down();
        return Fraction(new_up, new_down);
    }
    
    Fraction div(const Fraction &f1, const Fraction &f2)
    {
        long long new_up = f1.get_up() * f2.get_down();
        long long new_down = f1.get_down() * f2.get_up();
        return Fraction(new_up, new_down);
    }

task4.cpp:

#include "Fraction.h"
#include <iostream>

void test1();
void test2();

int main() {
    
    std::cout << "测试1: Fraction类基础功能测试\n";
    test1();

    std::cout << "\n测试2: 分母为0测试: \n";
    test2();
    
}

void test1() {
    using std::cout;
    using std::endl;   

    cout << "Fraction类测试: " << endl;
    cout << Fraction::doc << endl << endl;

    Fraction f1(5);
    Fraction f2(3, -4), f3(-18, 12);
    Fraction f4(f3);
    cout << "f1 = "; Fraction::output(f1); cout << endl;
    cout << "f2 = "; Fraction::output(f2); cout << endl;
    cout << "f3 = "; Fraction::output(f3); cout << endl;
    cout << "f4 = "; Fraction::output(f4); cout << endl;

    const Fraction f5(f4.negative());
    cout << "f5 = "; Fraction::output(f5); cout << endl;
    cout << "f5.get_up() = " << f5.get_up() 
        << ", f5.get_down() = " << f5.get_down() << endl;

    cout << "f1 + f2 = "; Fraction::output(Fraction::add(f1, f2)); cout << endl;
    cout << "f1 - f2 = "; Fraction::output(Fraction::sub(f1, f2)); cout << endl;
    cout << "f1 * f2 = "; Fraction::output(Fraction::mul(f1, f2)); cout << endl;
    cout << "f1 / f2 = "; Fraction::output(Fraction::div(f1, f2)); cout << endl;
    cout << "f4 + f5 = "; Fraction::output(Fraction::add(f4, f5)); cout << endl;    
}

void test2() {
    using std::cout;
    using std::endl;

    Fraction f6(42, 55), f7(0, 3);
    cout << "f6 = "; Fraction::output(f6); cout << endl;
    cout << "f7 = "; Fraction::output(f7); cout << endl;
    cout << "f6 / f7 = "; Fraction::output(Fraction::div(f6, f7)); cout << endl;
}

运行截图:

问题:

我使用的是静态成员，因为这些函数只在这个类里出现，应该和这个类绑定，
静态成员应该是那种和这个类强相关的情况下使用
使用命名空间代码无法复用。