实验2

实验任务1

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';
}

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;
}

 问题1  yes

 问题2  类 T 的普通构造函数用于创建新对象并初始化其成员；复制构造函数在用已有对象创建新对象时调用，进行拷贝；移动构造函数则从临时或即将销毁的对象中“转移”资源，避免不必要的拷贝，提升效率；析构函数在对象生命周期结束时自动调用，负责清理资源。  它们共同管理着对象的创建、复制、移动和销毁。

 问题3 报错，函数重复定义了

实验任务2

 Complex.cpp

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

using namespace std;

const string Complex::doc = "a simplified Complex class";

Complex::Complex() : real(0.0), imag(0.0) {}

Complex::Complex(double r) : real(r), imag(0.0) {}

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;
}

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

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

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

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

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

Complex.h

#ifndef COMPLEX_H
#define COMPLEX_H

#include <string>

class Complex {
private:
    double real;
    double imag;

public:
    static const std::string doc;

    Complex();
    Complex(double r);
    Complex(double r, double i);
    Complex(const Complex& other);

    double get_real() const;
    double get_imag() const;
    void add(const Complex& other);

    friend void output(const Complex& c);
    friend double abs(const Complex& c);
    friend Complex add(const Complex& c1, const Complex& c2);
    friend bool is_equal(const Complex& c1, const Complex& c2);
    friend bool is_not_equal(const Complex& c1, const Complex& c2);
};

void output(const Complex& c);
double abs(const Complex& c);
Complex add(const Complex& c1, const Complex& c2);
bool is_equal(const Complex& c1, const Complex& c2);
bool is_not_equal(const Complex& c1, const Complex& c2);

#endif

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;
}

 问题1  Complex更简洁

问题2-1 是。因为这些函数都需要直接访问复数的实部和虚部进行计算或输出。

问题2-2 否。标准库的abs是独立函数，通过public接口real()和imag()访问数据，不需要友元。

问题2-3 只在必要时使用friend：当函数需要访问私有数据但又不能作为成员函数时，或者要支持运算符重载且需要对称性时。

 

实验任务3

PlayContorl.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); 
void execute(ControlType cmd) const;
static int get_cnt();
private:
static int total_cnt;
};

PlayControl.cpp

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

int PlayerControl::total_cnt = 0;

PlayerControl::PlayerControl() {}

ControlType PlayerControl::parse(const std::string& control_str) {
    std::string lower_str = control_str;
    std::transform(lower_str.begin(), lower_str.end(), lower_str.begin(),
                   [](unsigned char c) { return std::tolower(c); });
    if (lower_str == "play") {
        total_cnt++;
        return ControlType::Play;
    } else if (lower_str == "pause") {
        total_cnt++;
        return ControlType::Pause;
    } else if (lower_str == "next") {
        total_cnt++;
        return ControlType::Next;
    } else if (lower_str == "prev") {
        total_cnt++;
        return ControlType::Prev;
    } else if (lower_str == "stop") {
        total_cnt++;
        return ControlType::Stop;
    } 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();
}

 

实验任务4

Fraction.cpp

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

using namespace std;

const 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 up, int down) : up(up), down(down) {
    if (down == 0) {
        throw invalid_argument("分母不能为0");
    }
    

    if (down < 0) {
        this->up = -up;
        this->down = -down;
    }
    
    simplify();
}

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);
}

int Fraction::gcd(int a, int b) const {
    a = abs(a);
    b = abs(b);
    while (b != 0) {
        int temp = b;
        b = a % b;
        a = temp;
    }
    return a;
}

void Fraction::simplify() {
    if (up == 0) {
        down = 1;
        return;
    }
    
    int common_divisor = gcd(up, down);
    up /= common_divisor;
    down /= common_divisor;
}
void output(const Fraction& f) {
    if (f.get_down() == 1) {
        cout << f.get_up();
    } else {
        cout << f.get_up() << "/" << f.get_down();
    }
}

Fraction add(const Fraction& f1, const Fraction& f2) {
    int new_up = f1.get_up() * f2.get_down() + f2.get_up() * f1.get_down();
    int new_down = f1.get_down() * f2.get_down();
    return Fraction(new_up, new_down);
}

Fraction sub(const Fraction& f1, const Fraction& f2) {
    int new_up = f1.get_up() * f2.get_down() - f2.get_up() * f1.get_down();
    int new_down = f1.get_down() * f2.get_down();
    return Fraction(new_up, new_down);
}

Fraction mul(const Fraction& f1, const Fraction& f2) {
    int new_up = f1.get_up() * f2.get_up();
    int new_down = f1.get_down() * f2.get_down();
    return Fraction(new_up, new_down);
}

Fraction div(const Fraction& f1, const Fraction& f2) {
    if (f2.get_up() == 0) {
        throw invalid_argument("分母不能为0");
    }
    int new_up = f1.get_up() * f2.get_down();
    int new_down = f1.get_down() * f2.get_up();
    return Fraction(new_up, new_down);
}

Fraction.h

#pragma once
#include <string>

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

    void simplify();    
    int gcd(int a, int b) const; 
};

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

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;
}

 自由函数 设计简洁