实验二

1.
#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();

    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();

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

//类T实现

//static成员数据类初始化
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';

}

#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;


}

　　

1.会报错

T(int a, int b) - 参数化构造函数

功能：根据提供的参数初始化对象

调用时机：创建对象时提供参数时调用

T(const T& other) - 拷贝构造函数

功能：通过复制已有对象来创建新对象

调用时机：对象初始化时使用另一个对象

T(T&& other) - 移动构造函数

功能：通过"移动"资源从临时对象或即将销毁的对象来创建新对象

调用时机：使用std::move或临时对象初始化时

3.可以正常运行

二。

#pragma once
#include<string>

class Complex
{
private:
    double real; //虚部
    double imag; //实部

public:
    static const std::string doc;

    //构造函数
    Complex(double r = 0.0, double i = 0.0); //默认构造函数
    Complex(const Complex& other);     //复制构造函数

    //成员函数
    double get_real() const;
    double get_imag() const;
    void add(const Complex& other);

    //友元函数
    friend bool is_equal(const Complex& c1, const Complex& c2);
    friend bool is_not_equal(const Complex& c1, const Complex& c2);
    friend double abs(const Complex& c);
    friend Complex add(const Complex& c1, Complex& c2);
    friend void output(const Complex& c);

};

　　

#include"complex.h"
#include<iostream>
#include<string>
#include<iomanip>
#include<cmath>

const std::string Complex::doc{ "a simple class sample" };

Complex::Complex(double r,double i):real(r),imag(i){}
Complex::Complex(const Complex& other):real(other.real),imag(other.imag){}


double Complex::get_real() const {

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

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

 bool is_equal(const Complex& c1, const Complex& c2) {
     if (c1.real == c2.real && c1.imag == c2.imag)
     {
         return true;
     }
     else
         return false;
}

 bool is_not_equal(const Complex& c1, const Complex& c2) {
     if (c1.real == c2.real && c1.imag == c2.imag)
     {
         return false;
     }
     else
         return true;
 }

 double abs(const Complex& c) {
     double mol;
     mol = sqrt(c.real * c.real + c.imag * c.imag);
     return mol;
 }

Complex add(const Complex& c1, Complex& c2) {
     return Complex(c1.real + c2.real, c1.imag + c2.imag);
 }

void output(const Complex& c) {
    if (c.imag >= 0)
    {
        std::cout << c.real <<" + "<< c.imag << "i";
    }
    else
    {

        std::cout << c.real << " - " << -c.imag << "i";
    }

}

　　

// 待补足头文件
#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;
}

　　

1.标准库模板类complex在使用形式上更简洁

2.1否，这些函数不需要设为友元

2.2标准库std::complex没有把abs设为友元

2.3紧密协作的类：两个类需要紧密交互时

三。

#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;
};

　　

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

int PlayerControl::total_cnt = 0;
PlayerControl::PlayerControl() {}


// 待补足
// 1. 将输入字符串转为小写，实现大小写不敏感
// 2. 匹配"play"/"pause"/"next"/"prev"/"stop"并返回对应枚举
// 3. 未匹配的字符串返回ControlType::Unknown
// 4. 每次成功调用parse时递增total_cnt
PlayerControl::ControlType PlayerControl::parse(const std::string& input) {

std::string lower_input = input;
std::transform(lower_input.begin(), lower_input.end(), lower_input.begin(),
[](unsigned char c) { return std::tolower(c); });
ControlType result = ControlType::Unknown;

if (lower_input == "play") {
result = ControlType::Play;
} else if (lower_input == "pause") {
result = ControlType::Pause;
} else if (lower_input == "next") {
result = ControlType::Next;
} else if (lower_input == "prev") {
result = ControlType::Prev;
} else if (lower_input == "stop") {
result = ControlType::Stop;
}
if (result != ControlType::Unknown) {
total_cnt++;
}

return result;
}

　　

#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();
}

　　

四。

#pragma once
#include<string>

class Fraction {
private:
    int up;
    int down;

    void reduce();//约分
    int gcd(int a, int b)const;//求最大公约数

public:
    static const std::string doc;

    //构造函数
    Fraction(int numerator = 0, int denominator = 1);
    Fraction(const Fraction& other);

    //成员函数
    int get_up()const;
    int get_down()const;
    Fraction negative()const;

    //友元函数声明

    friend void output(const Fraction& f);
    friend Fraction add(const Fraction& f1, const Fraction& f2);
    friend Fraction sub(const Fraction& f1, const Fraction& f2);
    friend Fraction mul(const Fraction& f1, const Fraction& f2);
    friend Fraction div(const Fraction& f1, const Fraction& f2);

};

　　

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


const std::string Fraction::doc =
"Fraction类 v 0.01版."
"目前仅支持分数对象的构造、输出、加 / 减 / 乘 / 除运算." ;


int Fraction::gcd(int a, int b)const {
    if (a < 0) {
        a = -a;
    }
    if (b < 0) {
        b = -b;
    }
    while (b)
    {
        int t = b;
        b = a % b;
        a = t;
    }
    return a;


}

void Fraction::reduce() {
    int common = gcd(up, down);
    if (common != 0)
    {
        up /= common;
        down /= common;
    }
}


    Fraction::Fraction(int numerator, int denominator) :up(numerator), down(denominator) {
        reduce();
    }

    Fraction::Fraction(const Fraction& other):up(other.up),down(other.down){}

    int Fraction::get_up()const {
        return up;
    }

    int Fraction::get_down()const {
        return down;
    }

    Fraction Fraction::negative()const {
        return Fraction(-up, down);
    }

    void output(const Fraction& f) {
        if (f.down == 0) {
            std::cout << "分母不能为0";
            return;
        }
        if (f.down == 1) {
            std::cout << f.up;
            return;
        }
        if (f.up < 0 && f.down < 0) {
            std::cout << -f.up << "/" << -f.down;
        }
        if (f.up > 0 && f.down > 0) {
            std::cout << f.up << "/" << f.down;
        }
        if (f.up < 0 && f.down > 0) {
            std::cout << f.up << "/" << f.down;
        }
        if (f.up > 0 && f.down < 0) {
            std::cout << -f.up << "/" << -f.down;
        }
    }

    Fraction add(const Fraction& f1, const Fraction& f2) {
        int _down = f1.down * f2.down;
        int _up = f1.up * f2.down + f2.up * f1.down;
        return Fraction(_up, _down);
    }

    Fraction sub(const Fraction& f1, const Fraction& f2) {
        int _down = f1.down * f2.down;
        int _up = f1.up * f2.down - f2.up * f1.down;
        return Fraction(_up, _down);
    }


    Fraction mul(const Fraction& f1, const Fraction& f2) {
        int _down = f1.down * f2.down;
        int _up = f1.up*f2.up;
        return Fraction(_up, _down);
    }


    Fraction div(const Fraction& f1, const Fraction& f2) {
        int _down = f1.down * f2.up;
        int _up = f1.up * f2.down;
        return Fraction(_up, _down);
    }

　　

#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;
}

　　

1，我选择的是友元方案，因为运算符重载的自然需求，具有对称性，直接访问私有成员避免函数调用开销