实验2

任务1源代码：

 1 #pragma once
 2 #include<string>
 3 
 4 //类T:声明
 5 class T
 6 {
 7     //对象属性、方法
 8 public:
 9     T(int x = 0, int y = 0);//普通构造函数
10     T(const T& t);//复制构造函数
11     T(T &&t);     //移动构造函数
12     ~T();
13 
14     void adjust(int ratio);//按系数成倍调整数据
15     void display() const;  //以(m1,m2)形式显示T类对象信息
16 
17 private:
18     int m1, m2;
19 
20     //类属性、方法
21 public:
22     static int get_cnt();//显示当前T类对象总数
23 public:
24     static const std::string doc;//类T的描述信息
25     static const int max_cnt;    //类T对象上限
26 
27 private:
28     static int cnt;  //当前T类对象数目
29 
30     //类T友元函数声明
31     friend void func();
32 };
33 
34 //普通函数声明
35 void func();

 1 #include"T.h"
 2 #include<iostream>
 3 #include<string>
 4 
 5 //类T实现
 6 
 7 //static成员数据类初始化
 8 const std::string T::doc{ "a simple class sample" };
 9 const int T::max_cnt = 999;
10 int T::cnt = 0;
11 
12 //类方法
13 int T::get_cnt() {
14     return cnt;
15 }
16 
17 //对象方法
18 T::T(int x, int y) :m1{ x }, m2{ y } {
19     ++cnt;
20     std::cout << "T constructor called.\n";
21 
22 }
23 T::T(const T& t) :m1{ t.m1 }, m2{ t.m2 } {
24     ++cnt;
25     std::cout << "T copy constructor called.\n";
26 }
27 
28 T::T(T&& t) :m1{ t.m1 }, m2{ t.m2 }
29 {
30     ++cnt;
31     std::cout << "T move constructor called.\n";
32 }
33 
34 T::~T() {
35     --cnt;
36     std::cout << "T destructor called.\n";
37 }
38 
39 void T::adjust(int ratio)
40 {
41     m1 *= ratio;
42     m2 *= ratio;
43 }
44 
45 void T::display()const
46 {
47     std::cout << "(" << m1 << "," << m2 << ")";
48 }
49 
50 //普通函数实现
51 void func()
52 {
53     T t5(42);
54     t5.m2 = 2049;
55     std::cout << "t5 = ";t5.display();std::cout << '\n';
56 
57 }

 1 #include "T.h"
 2 #include<iostream>
 3 
 4 void test_T();
 5 
 6 int main()
 7 {
 8     std::cout << "test class T:\n";
 9     test_T();
10 
11     std::cout << "\ntest friend func: \n";
12     func();
13 }
14 
15 void test_T()
16 {
17     using std::cout;
18     using std::endl;
19 
20     cout << "T info: " << T::doc << endl;
21     cout << "T objects'max count: " << T::max_cnt << endl;
22     cout << "T objects'current count: " << T::get_cnt() << endl << endl;
23 
24     T t1;
25     cout << "t1 = ";t1.display();cout << endl;
26 
27     T t2(3, 4);
28     cout << "t2 = ";t2.display();cout << endl;
29 
30     T t3(t2);
31     t3.adjust(2);
32     cout << "t3 = ";t3.display();cout << endl;
33 
34     T t4(std::move(t2));
35     cout << "t4 = ";t4.display();cout << endl;
36 
37     cout << "test: T objects'current count: " << T::get_cnt() << endl;
38 
39     
40 }

任务1截图：

问题：

1：vs2022中仍可运行，devc++中报错

2：

普通构造函数：作用为初始化对象，调用时机是当对象不提供任何实参或提供整数实参时调用

拷贝构造函数：作用是用已存在的对象的成员值初始化新对象，调用时机为用一个对象初始化另一个新对象时

移动构造函数：作用为调用一个即将销毁的对象资源，调用时机为用一个临时对象初始化新对象时

析构函数：作用为清理资源，调用时机为作用域结束

3：

vs可以正常运行

任务2源代码：

 1 #pragma once
 2 #include<string>
 3 
 4 class Complex
 5 {
 6 private:
 7     double real; //虚部
 8     double imag; //实部
 9 
10 public:
11     static const std::string doc;
12 
13     //构造函数
14     Complex(double r = 0.0, double i = 0.0); //默认构造函数
15     Complex(const Complex& other);     //复制构造函数
16 
17     //成员函数
18     double get_real() const;
19     double get_imag() const;
20     void add(const Complex& other);
21 
22     //友元函数
23     friend bool is_equal(const Complex& c1, const Complex& c2);
24     friend bool is_not_equal(const Complex& c1, const Complex& c2);
25     friend double abs(const Complex& c);
26     friend Complex add(const Complex& c1, Complex& c2);
27     friend void output(const Complex& c);
28 
29 };

 1 #include"complex.h"
 2 #include<iostream>
 3 #include<string>
 4 #include<iomanip>
 5 #include<cmath>
 6 
 7 const std::string Complex::doc{ "a simple class sample" };
 8 
 9 Complex::Complex(double r,double i):real(r),imag(i){}
10 Complex::Complex(const Complex& other):real(other.real),imag(other.imag){}
11 
12 
13 double Complex::get_real() const {
14 
15     return real;
16 }
17 double Complex::get_imag()const {
18     return imag;
19 }
20 
21 void Complex::add(const Complex& other) {
22     real += other.real;
23     imag += other.imag;
24 }
25 
26  bool is_equal(const Complex& c1, const Complex& c2) {
27      if (c1.real == c2.real && c1.imag == c2.imag)
28      {
29          return true;
30      }
31      else
32          return false;
33 }
34 
35  bool is_not_equal(const Complex& c1, const Complex& c2) {
36      if (c1.real == c2.real && c1.imag == c2.imag)
37      {
38          return false;
39      }
40      else
41          return true;
42  }
43 
44  double abs(const Complex& c) {
45      double mol;
46      mol = sqrt(c.real * c.real + c.imag * c.imag);
47      return mol;
48  }
49 
50 Complex add(const Complex& c1, Complex& c2) {
51      return Complex(c1.real + c2.real, c1.imag + c2.imag);
52  }
53 
54 void output(const Complex& c) {
55     if (c.imag >= 0)
56     {
57         std::cout << c.real <<" + "<< c.imag << "i";
58     }
59     else
60     {
61 
62         std::cout << c.real << " - " << -c.imag << "i";
63     }
64     
65 }

 1 // 待补足头文件
 2 #include"complex.h"
 3 #include <iostream>
 4 #include <iomanip>
 5 #include <complex>
 6 
 7 void test_Complex();
 8 void test_std_complex();
 9 
10 int main() {
11     std::cout << "*******测试1: 自定义类Complex*******\n";
12     test_Complex();
13 
14     std::cout << "\n*******测试2: 标准库模板类complex*******\n";
15     test_std_complex();
16 }
17 
18 void test_Complex() {
19     using std::cout;
20     using std::endl;
21     using std::boolalpha;
22 
23     cout << "类成员测试: " << endl;
24     cout << Complex::doc << endl << endl;
25 
26     cout << "Complex对象测试: " << endl;
27     Complex c1;
28     Complex c2(3, -4);
29     Complex c3(c2);
30     Complex c4 = c2;
31     const Complex c5(3.5);
32 
33     cout << "c1 = "; output(c1); cout << endl;
34     cout << "c2 = "; output(c2); cout << endl;
35     cout << "c3 = "; output(c3); cout << endl;
36     cout << "c4 = "; output(c4); cout << endl;
37     cout << "c5.real = " << c5.get_real()
38         << ", c5.imag = " << c5.get_imag() << endl << endl;
39 
40     cout << "复数运算测试: " << endl;
41     cout << "abs(c2) = " << abs(c2) << endl;
42     c1.add(c2);
43     cout << "c1 += c2, c1 = "; output(c1); cout << endl;
44     cout << boolalpha;
45     cout << "c1 == c2 : " << is_equal(c1, c2) << endl;
46     cout << "c1 != c2 : " << is_not_equal(c1, c2) << endl;
47     c4 = add(c2, c3);
48     cout << "c4 = c2 + c3, c4 = "; output(c4); cout << endl;
49 }
50 
51 void test_std_complex() {
52     using std::cout;
53     using std::endl;
54     using std::boolalpha;
55 
56     cout << "std::complex<double>对象测试: " << endl;
57     std::complex<double> c1;
58     std::complex<double> c2(3, -4);
59     std::complex<double> c3(c2);
60     std::complex<double> c4 = c2;
61     const std::complex<double> c5(3.5);
62 
63     cout << "c1 = " << c1 << endl;
64     cout << "c2 = " << c2 << endl;
65     cout << "c3 = " << c3 << endl;
66     cout << "c4 = " << c4 << endl;
67 
68     cout << "c5.real = " << c5.real()
69         << ", c5.imag = " << c5.imag() << endl << endl;
70 
71     cout << "复数运算测试: " << endl;
72     cout << "abs(c2) = " << abs(c2) << endl;
73     c1 += c2;
74     cout << "c1 += c2, c1 = " << c1 << endl;
75     cout << boolalpha;
76     cout << "c1 == c2 : " << (c1 == c2) << endl;
77     cout << "c1 != c2 : " << (c1 != c2) << endl;
78     c4 = c2 + c3;
79     cout << "c4 = c2 + c3, c4 = " << c4 << endl;
80 }

任务2截图：

问题：

1：标准库模版更简洁，函数和运算内在有关联

2.1:asb不是友元函数,因为可以通过公共成员函数获取数据

2.2：函数无法通过公用接口完成操作时

2.3:显式声明构造函数，比如在复制构造函数前加关键字explicit修饰

任务3源代码：

 1 #pragma once
 2 #include <string>
 3 
 4 enum class ControlType { Play, Pause, Next, Prev, Stop, Unknown };
 5 
 6 class PlayerControl {
 7 public:
 8     PlayerControl();
 9 
10     ControlType parse(const std::string& control_str);   // 实现std::string --> ControlType转换
11     void execute(ControlType cmd) const;   // 执行控制操作（以打印输出模拟）       
12 
13     static int get_cnt();
14 
15 private:
16     static int total_cnt;
17 };

 1 #include "PlayerControl.h"
 2 #include <iostream>
 3 #include <algorithm>   
 4 #include <cctype>
 5 
 6 int PlayerControl::total_cnt = 0;
 7 PlayerControl::PlayerControl() {}
 8 
 9 
10 // 待补足
11 // 1. 将输入字符串转为小写，实现大小写不敏感
12 // 2. 匹配"play"/"pause"/"next"/"prev"/"stop"并返回对应枚举
13 // 3. 未匹配的字符串返回ControlType::Unknown
14 // 4. 每次成功调用parse时递增total_cnt
15 ControlType PlayerControl::parse(const std::string& control_str) {
16     std::string str = control_str;
17     std::transform(str.begin(), str.end(), str.begin(), ::tolower);
18     ++total_cnt;
19     if (str == "play")return ControlType::Play;
20     if (str == "pause")return ControlType::Pause;
21     if (str == "next")return ControlType::Next;
22     if (str == "prev")return ControlType::Prev;
23     if (str == "stop")return ControlType::Stop;
24     return ControlType::Unknown;
25 }
26 void PlayerControl::execute(ControlType cmd) const {
27     switch (cmd) {
28     case ControlType::Play:
29         std::cout << "[play] Playing music...\n"; break;
30     case ControlType::Pause: 
31         std::cout << "[Pause] Music paused\n";break;
32     case ControlType::Next: 
33         std::cout << "[Next] Skipping to next track\n"; break;
34     case ControlType::Prev: 
35         std::cout << "[Prev] Back to previous track\n"; break;
36     case ControlType::Stop: 
37         std::cout << "[Stop] Music stopped\n"; break;
38     default: 
39         std::cout << "[Error] unknown control\n"; break;
40     }
41 }
42 int PlayerControl::get_cnt() {
43     return total_cnt;
44 }

 1 #include "PlayerControl.h"
 2 #include <iostream>
 3 
 4 void test() {
 5     PlayerControl controller;
 6     std::string control_str;
 7     std::cout << "Enter Control: (play/pause/next/prev/stop/quit):\n";
 8 
 9     while (std::cin >> control_str) {
10         if (control_str == "quit")
11             break;
12 
13         ControlType cmd = controller.parse(control_str);
14         controller.execute(cmd);
15         std::cout << "Current Player control: " << PlayerControl::get_cnt() << "\n\n";
16     }
17 }
18 
19 int main() {
20     test();
21 }

任务3截图:

任务4源代码：

 1 #pragma once
 2 #include<string>
 3 
 4 class Fraction {
 5 private:
 6     int up;
 7     int down;
 8 
 9     void reduce();//约分
10     int gcd(int a, int b)const;//求最大公约数
11 
12 public:
13     static const std::string doc;
14 
15     //构造函数
16     Fraction(int numerator = 0, int denominator = 1);
17     Fraction(const Fraction& other);
18 
19     //成员函数
20     int get_up()const;
21     int get_down()const;
22     Fraction negative()const;
23 
24     //友元函数声明
25 
26     friend void output(const Fraction& f);
27     friend Fraction add(const Fraction& f1, const Fraction& f2);
28     friend Fraction sub(const Fraction& f1, const Fraction& f2);
29     friend Fraction mul(const Fraction& f1, const Fraction& f2);
30     friend Fraction div(const Fraction& f1, const Fraction& f2);
31 
32 };

  1 #include"Fraction.h"
  2 #include<iostream>
  3 #include<cmath>
  4 
  5 
  6 const std::string Fraction::doc = 
  7 "Fraction类 v 0.01版."  
  8 "目前仅支持分数对象的构造、输出、加 / 减 / 乘 / 除运算." ;
  9 
 10 
 11 int Fraction::gcd(int a, int b)const {
 12     if (a < 0) {
 13         a = -a;
 14     }
 15     if (b < 0) {
 16         b = -b;
 17     }
 18     while (b)
 19     {
 20         int t = b;
 21         b = a % b;
 22         a = t;
 23     }
 24     return a;
 25 
 26 
 27 }
 28 
 29 void Fraction::reduce() {
 30     int common = gcd(up, down);
 31     if (common != 0)
 32     {
 33         up /= common;
 34         down /= common;
 35     }
 36 }
 37 
 38 
 39     Fraction::Fraction(int numerator, int denominator) :up(numerator), down(denominator) {
 40         reduce();
 41     }
 42 
 43     Fraction::Fraction(const Fraction& other):up(other.up),down(other.down){}
 44 
 45     int Fraction::get_up()const {
 46         return up;
 47     }
 48 
 49     int Fraction::get_down()const {
 50         return down;
 51     }
 52 
 53     Fraction Fraction::negative()const {
 54         return Fraction(-up, down);
 55     }
 56 
 57     void output(const Fraction& f) {
 58         if (f.down == 0) {
 59             std::cout << "分母不能为0";
 60             return;
 61         }
 62         if (f.down == 1) {
 63             std::cout << f.up;
 64             return;
 65         }
 66         if (f.up < 0 && f.down < 0) {
 67             std::cout << -f.up << "/" << -f.down;
 68         }
 69         if (f.up > 0 && f.down > 0) {
 70             std::cout << f.up << "/" << f.down;
 71         }
 72         if (f.up < 0 && f.down > 0) {
 73             std::cout << f.up << "/" << f.down;
 74         }
 75         if (f.up > 0 && f.down < 0) {
 76             std::cout << -f.up << "/" << -f.down;
 77         }
 78     }
 79 
 80     Fraction add(const Fraction& f1, const Fraction& f2) {
 81         int _down = f1.down * f2.down;
 82         int _up = f1.up * f2.down + f2.up * f1.down;
 83         return Fraction(_up, _down);
 84     }
 85 
 86     Fraction sub(const Fraction& f1, const Fraction& f2) {
 87         int _down = f1.down * f2.down;
 88         int _up = f1.up * f2.down - f2.up * f1.down;
 89         return Fraction(_up, _down);
 90     }
 91 
 92 
 93     Fraction mul(const Fraction& f1, const Fraction& f2) {
 94         int _down = f1.down * f2.down;
 95         int _up = f1.up*f2.up;
 96         return Fraction(_up, _down);
 97     }
 98 
 99 
100     Fraction div(const Fraction& f1, const Fraction& f2) {
101         int _down = f1.down * f2.up;
102         int _up = f1.up * f2.down;
103         return Fraction(_up, _down);
104     }

 1 #include "Fraction.h"
 2 #include <iostream>
 3 
 4 
 5 void test1();
 6 void test2();
 7 
 8 int main() {
 9     std::cout << "测试1: Fraction类基础功能测试\n";
10     test1();
11     std::cout << "\n测试2: 分母为0测试: \n";
12     test2();
13 }
14 void test1() {
15     using std::cout;
16     using std::endl;
17     cout << "Fraction类测试: " << endl;
18     cout << Fraction::doc << endl << endl;
19     Fraction f1(5);
20     Fraction f2(3, -4), f3(-18, 12);
21     Fraction f4(f3);
22     cout << "f1 = "; output(f1); cout << endl;
23     cout << "f2 = "; output(f2); cout << endl;
24     cout << "f3 = "; output(f3); cout << endl;
25     cout << "f4 = "; output(f4); cout << endl;
26     const Fraction f5(f4.negative());
27     cout << "f5 = "; output(f5); cout << endl;
28     cout << "f5.get_up() = " << f5.get_up()
29         << ", f5.get_down() = " << f5.get_down() << endl;
30     cout << "f1 + f2 = "; output(add(f1, f2)); cout << endl;
31     cout << "f1 - f2 = "; output(sub(f1, f2)); cout << endl;
32     cout << "f1 * f2 = "; output(mul(f1, f2)); cout << endl;
33     cout << "f1 / f2 = "; output(div(f1, f2)); cout << endl;
34     cout << "f4 + f5 = "; output(add(f4, f5)); cout << endl;
35 }
36 void test2() {
37     using std::cout;
38     using std::endl;
39     Fraction f6(42, 55), f7(0, 3);
40     cout << "f6 = "; output(f6); cout << endl;
41     cout << "f7 = "; output(f7); cout << endl;
42     cout << "f6 / f7 = "; output(div(f6, f7)); cout << endl;
43 }

任务4截图：

问题：我选择的是友元函数方案；

因为分数运算需要同时访问两个操作数的分子分母，友元函数可以直接访问私有成员

posted @ 2025-10-26 22:39 杨启霖阅读(0) 评论(0) 收藏举报

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实验2

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