实验二

任务一

源代码

T.h

#pragma once

#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';
}

task.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;
}

效果

1.不能

T.h内部的friend void func()仅声明它是友元，不会在全局中声明func()

2.

9：初始化T的对象，给m1,m2赋值   在创造T的对象时

10：复制原有T类对象初始化新的T对象   一个对象初始化另一个对象时

11：使用临时对象的资源来初始化新对象   右值初始化对象时

12：在对象生命周期结束时，执行资源清理操作  对象生命周期结束时

3.

将该定义从T.cpp剪切至T.h后，T.h被T.cpp和task1.cpp同时包括，两个文件各自生成不同定义

任务二

源代码

Complex.h

#pragma once
#include <iostream>
#include <iomanip>
#include <complex>
#include <string>
class Complex {
public:
    Complex();
    Complex(double a);
    Complex(double a, double b);
    Complex(const Complex& i);
private:
    double real = 0, imag = 0;
public:
    static const std::string doc;
    double get_real()const;
    double get_imag()const;
    void add(Complex& i);
    friend void output(Complex& i);
    friend double abs(Complex& i);
    friend Complex add(Complex& i1, Complex& i2);
    friend bool is_equal(Complex& i1, Complex& i2);
    friend bool is_not_equal(Complex& i1, Complex& i2);
};
void output(Complex& i);
double abs(Complex& i);
Complex add(Complex& i1, Complex& i2);
bool is_equal(Complex& i1, Complex& i2);
bool is_not_equal(Complex& i1, Complex& i2);

Complex.cpp

#include"Complex.h"
#include <iostream>
#include <iomanip>
#include <complex>
#include <string>
const std::string Complex::doc{ "a simplified complex class" };
double Complex::get_real()const {
    return real;
}
double Complex::get_imag()const {
    return imag;
}
void Complex::add(Complex& i) {
    real += i.real;
    imag += i.imag;
}
Complex::Complex() {};
Complex::Complex(double a) {
    real = a;
}
Complex::Complex(double a, double b) {
    real = a, imag = b;
}
Complex::Complex(const Complex& i) {
    real = i.real, imag = i.imag;
}
void output(Complex& i) {
    if (i.imag >= 0) {
        std::cout << i.real << "+" << i.imag << "i" << std::endl;
    }
    else {
        std::cout << i.real << i.imag << "i" << std::endl;
    }
}
double abs(Complex& i) {
    return sqrt(i.real * i.real + i.imag * i.imag);
}
Complex add(Complex& i1, Complex& i2) {
    Complex i;
    i.real = i1.real + i2.real;
    i.imag = i1.imag + i2.imag;
    return i;
}
bool is_equal(Complex& i1, Complex& i2) {
    if (i1.get_real() == i2.get_real() && i1.get_imag() == i2.get_imag()) {
        return true;
    }
    else {
        return false;
    }
}
bool is_not_equal(Complex& i1, Complex& i2) {
    if (i1.get_real() == i2.get_real() && i1.get_imag() == i2.get_imag()) {
        return false;
    }
    else {
        return true;
    }
}

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;
}

效果

1.标准库模版类更整洁，有内在关联

2.1 是，因为他们需要实部与虚部进行操作，需要设置友元来访问

2.2 不是 ，abs是普通函数，不用访问私有数据，所以不用设为友元

2.3 直接访问类私有数据

3.在类中显示Complex(const Complex &other),且访问权限为public在函数内复制实部与虚部的值

任务三

源代码

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 temp = control_str;
    std::transform(temp.begin(), temp.end(), temp.begin(), [](unsigned char c) {return std::tolower(c); });
    ControlType res;
    if (temp == "play")
        res = ControlType::Play;
    else if (temp == "pause")
        res = ControlType::Pause;
    else if (temp == "next")
        res = ControlType::Next;
    else if (temp == "prev")
        res = ControlType::Prev;
    else if (temp == "stop")
        res = ControlType::Stop;
    else
        res = ControlType::Unknown;

    total_cnt++;
    return res;
    
}

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();
}

效果

任务4

源代码

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 = "; output(f1); cout << endl;
    cout << "f2 = "; output(f2); cout << endl;
    cout << "f3 = "; output(f3); cout << endl;
    cout << "f4 = "; output(f4); cout << endl;

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

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

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

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

Fraction.h

#pragma once
#include <string>

class Fraction {
public:
    static const std::string doc;          

    
    Fraction(int up = 0, int down = 1);  
    Fraction(const Fraction& rhs);         

   
    int get_up()   const { return up_; }
    int get_down() const { return down_; }

    
    Fraction negative() const;

private:
    int up_;     
    int down_;   

    
    void simplify();
};


namespace frac {
    void output(const Fraction& f);   
    Fraction add(const Fraction& a, const Fraction& b);
    Fraction sub(const Fraction& a, const Fraction& b);
    Fraction mul(const Fraction& a, const Fraction& b);
    Fraction div(const Fraction& a, const Fraction& b);
}

Fraction.cpp

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

using std::cout;
using std::endl;

const std::string Fraction::doc =
"Fraction类v0.01版\n"
"目前仅支持分数对象的构造、输出、加/减/乘/除运算";


static int gcd(int a, int b) {
    a = std::abs(a);
    b = std::abs(b);
    while (b != 0) {
        int t = b;
        b = a % b;
        a = t;
    }
    return a == 0 ? 1 : a;
}


Fraction::Fraction(int up, int down)
    : up_(up), down_(down) {
    if (down == 0)
        throw std::invalid_argument("分母不能为0");
    simplify();
}

Fraction::Fraction(const Fraction& rhs)
    : up_(rhs.up_), down_(rhs.down_) {
}


void Fraction::simplify() {
    if (down_ < 0) {         
        up_ = -up_;
        down_ = -down_;
    }
    int g = gcd(up_, down_);
    up_ /= g;
    down_ /= g;
}


Fraction Fraction::negative() const {
    return Fraction(-up_, down_);
}


namespace frac {

    void output(const Fraction& f) {
        cout << f.get_up() << '/' << f.get_down();
    }

    Fraction add(const Fraction& a, const Fraction& b) {
        int up = a.get_up() * b.get_down() + b.get_up() * a.get_down();
        int down = a.get_down() * b.get_down();
        return Fraction(up, down);
    }

    Fraction sub(const Fraction& a, const Fraction& b) {
        int up = a.get_up() * b.get_down() - b.get_up() * a.get_down();
        int down = a.get_down() * b.get_down();
        return Fraction(up, down);
    }

    Fraction mul(const Fraction& a, const Fraction& b) {
        int up = a.get_up() * b.get_up();
        int down = a.get_down() * b.get_down();
        return Fraction(up, down);
    }

    Fraction div(const Fraction& a, const Fraction& b) {
        if (b.get_up() == 0)
            throw std::invalid_argument("除数分子为0");
        int up = a.get_up() * b.get_down();
        int down = a.get_down() * b.get_up();
        return Fraction(up, down);
    }

} 

效果

1.命名空间+自由函数

通过公用接口get_up()/get_down()已可以完成计算，不用访问任何的私有成员，没必要用friend破坏封装