实验2 类和对象

任务1

t.h

 1 #pragma once
 2 
 3 #include <string>
 4 
 5 // 类T: 声明
 6 class T {
 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();           // 析构函数
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 
24 public:
25     static const std::string doc;       // 类T的描述信息
26     static const int max_cnt;           // 类T对象上限
27 
28 private:
29     static int cnt;         // 当前T类对象数目
30 
31 // 类T友元函数声明
32     friend void func();
33 };
34 
35 // 普通函数声明
36 void func();
View Code

t.cpp

 1 // 类T: 实现
 2 // 普通函数实现
 3 
 4 #include "t.h"
 5 #include <iostream>
 6 #include <string>
 7 
 8 using std::cout;
 9 using std::endl;
10 using std::string;
11 
12 // static成员数据类外初始化
13 const std::string T::doc{"a simple class sample"};
14 const int T::max_cnt = 999;
15 int T::cnt = 0;
16 
17 
18 // 对象方法
19 T::T(int x, int y): m1{x}, m2{y} { 
20     ++cnt; 
21     cout << "T constructor called.\n";
22 } 
23 
24 T::T(const T &t): m1{t.m1}, m2{t.m2} {
25     ++cnt;
26     cout << "T copy constructor called.\n";
27 }
28 
29 T::T(T &&t): m1{t.m1}, m2{t.m2} {
30     ++cnt;
31     cout << "T move constructor called.\n";
32 }    
33 
34 T::~T() {
35     --cnt;
36     cout << "T destructor called.\n";
37 }           
38 
39 void T::adjust(int ratio) {
40     m1 *= ratio;
41     m2 *= ratio;
42 }    
43 
44 void T::display() const {
45     cout << "(" << m1 << ", " << m2 << ")" ;
46 }     
47 
48 // 类方法
49 int T::get_cnt() {
50    return cnt;
51 }
52 
53 // 友元
54 void func() {
55     T t5(42);
56     t5.m2 = 2049;
57     cout << "t5 = "; t5.display(); cout << endl;
58 }
View Code

task1.cpp

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

运行截图

 问题1：

去掉line36，不能正确运行，报错信息为：

 可能的原因为：func只在类T中声明为友元函数，未声明为普通函数

 

 问题2：

普通构造函数：构造函数用于初始化对象的成员变量，分配资源或执行任何启动操作。

复制构造函数：用于通过已有对象创建新对象，通常采用传值方式。

移动构造函数：用于高效地转移资源，通常在对象的资源很重的情况下使用，避免不必要的拷贝。

构造函数在创建对象时自动调用；析构函数在对象的生命周期结束时自动调用。

 

问题3：

不能正确编译运行，报错信息为：

 

 

 

任务2

 Complex.h

 1 #pragma once
 2 #include <iostream>  
 3 #include <cmath>  
 4 
 5 class Complex {
 6 public:
 7     Complex(); // 默认构造函数   
 8     Complex(double real, double imag); // 构造函数 
 9     Complex(double real) ; // 单参构造函数  
10     Complex(const Complex& other); // 拷贝构造函数  
11 
12     double get_real() const; // 返回实部  
13     double get_imag() const; // 返回虚部  
14     Complex add(const Complex& c);
15     friend Complex add(const Complex& c1, const Complex& c2) ; // 复数相加  
16     friend bool is_equal(const Complex& c1, const Complex& c2) ; // 判断相等  
17     friend bool is_not_equal(const Complex& c1, const Complex& c2) ; // 判断不相等  
18     friend double abs(Complex &c) ; // 取模  
19     friend void output(const Complex &c) ; // 输出复数  
20 
21     static std::string doc ;
22 private:
23     double real; // 实部  
24     double imag; // 虚部  
25 };
View Code

Complex.cpp

 1 #include "Complex.h"  
 2 #include<iostream>
 3 
 4 // 默认构造函数  
 5 Complex::Complex() : real(0), imag(0) {}
 6 
 7 
 8 // 构造函数  
 9 Complex::Complex(double real, double imag) : real(real), imag(imag) {}
10 
11 //单参构造函数
12 Complex::Complex(double real): real(real), imag(0) {}
13 
14 // 拷贝构造函数  
15 Complex::Complex(const Complex& other) : real(other.real), imag(other.imag) {}
16 
17 // 返回实部  
18 double Complex::get_real() const {
19     return real;
20 }
21 
22 // 返回虚部  
23 double Complex::get_imag() const {
24     return imag;
25 }
26 
27 Complex Complex::add(const Complex& c) {
28     return Complex(real + c.real, imag + c.imag);
29 }
30 
31 // 复数相加  
32 Complex add(const Complex& c1, const Complex& c2)  {
33     return Complex(c1.real + c2.real, c1.imag + c2.imag);
34 }
35 
36 // 判断相等  
37 bool is_equal(const Complex& c1, const Complex& c2)  {
38     return (c1.real == c2.real && c1.imag == c2.imag);
39 }
40 
41 // 判断不相等  
42  bool is_not_equal(const Complex & c1, const Complex & c2) {
43     return !is_equal(c1,c2);
44 }
45 
46 // 取模  
47 double abs(Complex &c)  {
48     return sqrt(c.real * c.real + c.imag * c.imag);
49 }
50 
51 // 输出复数  
52 void output(const Complex &c)  {
53     std::cout << c.real << (c.imag >= 0 ? "+" : "") << c.imag << "i";
54 }
55 
56  std::string Complex::doc="A simplified class" ;
View Code

Main.cpp

 1 #include "Complex.h" 
 2 #include <iostream>
 3 
 4 using std::cout;
 5 using std::endl;
 6 using std::boolalpha;
 7 
 8 void test() {
 9     cout << "类成员测试: " << endl;
10     cout << Complex::doc << endl;
11 
12     cout << endl;
13 
14     cout << "Complex对象测试: " << endl;
15     Complex c1;
16     Complex c2(3, -4);
17     const Complex c3(3.5);
18     Complex c4(c3);
19 
20     cout << "c1 = "; output(c1); cout << endl;
21     cout << "c2 = "; output(c2); cout << endl;
22     cout << "c3 = "; output(c3); cout << endl;
23     cout << "c4 = "; output(c4); cout << endl;
24     cout << "c4.real = " << c4.get_real() << ", c4.imag = " << c4.get_imag() << endl;
25 
26     cout << endl;
27 
28     cout << "复数运算测试: " << endl;
29     cout << "abs(c2) = " << abs(c2) << endl;
30     c1.add(c2);
31     cout << "c1 += c2, c1 = "; output(c1); cout << endl;
32     cout << boolalpha;
33     cout << "c1 == c2 : " << is_equal(c1, c2) << endl;
34     cout << "c1 != c3 : " << is_not_equal(c1, c3) << endl;
35     c4 =add(c2, c3);
36     cout << "c4 = c2 + c3, c4 = "; output(c4); cout << endl;
37 }
38 
39 int main() {
40     test();
41 }
View Code

 运行截图：

 

 

任务3

task3.cpp

 1 #include <iostream>
 2 #include <complex>
 3 
 4 using std::cout;
 5 using std::endl;
 6 using std::boolalpha;
 7 using std::complex;
 8 
 9 void test() {
10     cout << "标准库模板类comple测试: " << endl;
11     complex<double> c1;
12     complex<double> c2(3, -4);
13     const complex<double> c3(3.5);
14     complex<double> c4(c3);
15 
16     cout << "c1 = " << c1 << endl;
17     cout << "c2 = " << c2 << endl;
18     cout << "c3 = " << c3 << endl;
19     cout << "c4 = " << c4 << endl;
20     cout << "c4.real = " << c4.real() << ", c4.imag = " << c4.imag() << endl;
21     cout << endl;
22 
23     cout << "复数运算测试: " << endl;
24     cout << "abs(c2) = " << abs(c2) << endl;
25     c1 += c2;
26     cout << "c1 += c2, c1 = " << c1 << endl;
27     cout << boolalpha;
28     cout << "c1 == c2 : " << (c1 == c2) << endl;
29     cout << "c1 != c3 : " << (c1 != c3) << endl;
30     c4 = c2 + c3;
31     cout << "c4 = c2 + c3, c4 = " << c4 << endl;
32 }
33 
34 int main() {
35     test();
36 }
View Code

运行结果：

接口有默认构造函数，普通构造函数，单参构造函数，复制构造函数，real,imag,abs,复数加法，判断复数是否相等

对比任务2：

1.c1 += c2代替c1.add(c2)，(c1 == c2)代替is_equal(c1, c2)，(c1 != c3)代替is_not_equal(c1, c3)，对象名能直接输出

 2：可以用运算符重载来简化类的操作

 

任务4

Fraction.h

 1 #pragma once
 2 #include <iostream> 
 3 #include <numeric> 
 4   
 5   class Fraction { 
 6   private: 
 7     int up;   // 分子 
 8     int down; // 分母 
 9      
10     void simplify(); // 简化分数 
11  
12  public: 
13     static const std::string doc; // 描述信息 
14 
15     Fraction(int numerator = 0, int denominator = 1); // 构造函数 
16     Fraction(const Fraction &f); // 拷贝构造函数 
17 
18     int get_up() const; // 返回分子 
19     int get_down() const; // 返回分母 
20     Fraction negative() const; // 求负 
21  
22     friend void output(const Fraction &f); //输出 
23     friend Fraction add(const Fraction &f1, const Fraction &f2); 
24     friend Fraction sub(const Fraction &f1, const Fraction &f2); 
25     friend Fraction mul(const Fraction &f1, const Fraction &f2); 
26     friend Fraction div(const Fraction &f1, const Fraction &f2); 
27     
28     
29  }; 
30  
31  int gcd1(int a,int b);
View Code

Fraction.cpp

 1 #include "Fraction.h" 
 2  #include<iostream>
 3  
 4  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。"; 
 5  
 6  
 7  int gcd1(int a,int b)
 8  {
 9     return b==0?a:gcd1(b,a%b);
10  }
11  
12  Fraction::Fraction(int numerator, int denominator) : up(numerator), down(denominator) { 
13     if (down == 0) { 
14         std::cout<<"分母不能为0"<<std::endl;
15      }
16      simplify(); 
17  } 
18  
19  Fraction::Fraction(const Fraction &f) : up(f.up), down(f.down) {} 
20  
21  void Fraction::simplify() { 
22      int gcd = gcd1(up, down); 
23      up /= gcd; 
24      down /= gcd; 
25      if (down < 0) { // 保持负号在分子上 
26          up = -up; 
27          down = -down; 
28      } 
29  } 
30  
31  int Fraction::get_up() const { 
32      return up; 
33  } 
34  
35  int Fraction::get_down() const { 
36      return down; 
37  } 
38  
39  Fraction Fraction::negative() const { 
40      return Fraction(-up, down); 
41  } 
42  
43  void output(const Fraction &f){
44      if(f.down!=0){
45      
46      if(f.down==1)
47         std::cout<<f.up<<std::endl;
48      else
49        std::cout<<f.up<<"/"<<f.down<<std::endl;
50    }
51  }
52  
53  Fraction add(const Fraction &f1, const Fraction &f2) { 
54      return Fraction(f1.up * f2.down + f2.up * f1.down, f1.down * f2.down); 
55  } 
56  
57  Fraction sub(const Fraction &f1, const Fraction &f2) { 
58      return Fraction(f1.up * f2.down - f2.up * f1.down, f1.down * f2.down); 
59  } 
60  
61  Fraction mul(const Fraction &f1, const Fraction &f2) { 
62      return Fraction(f1.up * f2.up, f1.down * f2.down); 
63  } 
64  
65  Fraction div(const Fraction &f1, const Fraction &f2) { 
66      if (f2.up == 0) { 
67          std::cout<<"分母不能为0"<<std::endl; 
68      }
69      else 
70          return Fraction(f1.up * f2.down, f1.down * f2.up); 
71  } 
72
View Code

task4.cpp

 1 #include "Fraction.h"
 2  #include <iostream>
 3   
 4  using std::cout;
 5  using std::endl;
 6  
 7  
 8  void test1() {
 9  cout << "Fraction类测试: " << endl;
10  cout << Fraction::doc << endl << endl;
11  
12  Fraction f1(5);
13  Fraction f2(3, -4), f3(-18, 12);
14  Fraction f4(f3);
15  cout << "f1 = "; output(f1); cout << endl;
16  cout << "f2 = "; output(f2); cout << endl;
17  cout << "f3 = "; output(f3); cout << endl;
18  cout << "f4 = "; output(f4); cout << endl;
19 
20  Fraction f5(f4.negative());
21  cout << "f5 = "; output(f5); cout << endl;
22  cout << "f5.get_up() = " << f5.get_up() << ", f5.get_down() = " << f5.get_down() << endl;
23 
24  cout << "f1 + f2 = "; output(add(f1, f2)); cout << endl;
25  cout << "f1 - f2 = "; output(sub(f1, f2)); cout << endl;
26  cout << "f1 * f2 = "; output(mul(f1, f2)); cout << endl;
27  cout << "f1 / f2 = "; output(div(f1, f2)); cout << endl;
28  cout << "f4 + f5 = "; output(add(f4, f5)); cout << endl;
29  }
30  
31  void test2() {
32  Fraction f6(42, 55), f7(0, 3);
33  cout << "f6 = "; output(f6); cout << endl;
34  cout << "f7 = "; output(f7); cout << endl;
35  cout << "f6 / f7 = "; output(div(f6, f7)); cout << endl;
36 }
37  
38 int main() {
39  cout << "测试1: Fraction类基础功能测试\n";
40  test1();
41  
42  cout << "\n测试2: 分母为0测试: \n";
43  test2();
44  }
View Code

运行截图：

 

 

任务5

 account.h

 1 #pragma once
 2 class SavingsAccount {
 3     private:
 4         int id;
 5         double balance;
 6         double rate;
 7         int lastDate;
 8         double accumulation;
 9         static double total;
10         void record(int date,double amount);
11         double accumulate(int date) const {
12             return accumulation+balance*(date-lastDate);
13         } 
14     public:
15         SavingsAccount(int date,int id,double rate);
16         int getId() const {return id;}
17         double getBalance() const {return balance;}
18         double getRate() const {return rate;}
19         static double getTotal() {return total;}
20         void deposit(int date,double amount);
21         void withdraw(int date,double amount);
22         void settle(int date);
23         void show() const;
24 };
View Code

account.cpp

 1 #include "account.h"
 2 #include <cmath>
 3 #include <iostream>
 4 using namespace std;
 5 
 6 double SavingsAccount::total=0;
 7 SavingsAccount::SavingsAccount(int date,int id,double rate):id(id),balance(0),rate(rate),lastDate(date),accumulation(0){
 8     cout<<date<<"\t#"<<id<<" is created"<<endl;
 9 }
10 void SavingsAccount::record(int date,double amount) {
11     accumulation=accumulate(date);
12     lastDate=date;
13     amount=floor(amount*100+0.5)/100;
14     balance+=amount;
15     total+=amount;
16     cout<<date<<"\t#"<<id<<"\t"<<amount<<"\t"<<balance<<endl;
17 }
18 
19 void SavingsAccount::deposit(int date,double amount) {
20     record(date,amount);
21 }
22 
23 
24 void SavingsAccount::withdraw(int date,double amount) {
25     if(amount>getBalance())
26         cout<<"Error:not enough money"<<endl;
27     else
28         record(date,-amount);
29 }
30 void SavingsAccount::settle(int date) {
31     double interest=accumulate(date)*rate/365;
32     if(interest!=0)
33         record(date,interest);
34     accumulation=0;
35 }
36 void SavingsAccount::show() const {
37     cout<<"#"<<id<<"\tBalance:"<<balance;
38 }
39 
40
View Code

5_11.cpp

 1 #include "account.h"
 2 #include <iostream>
 3 using namespace std;
 4 int main()
 5 {
 6     SavingsAccount sa0(1,21325302,0.015);
 7     SavingsAccount sa1(1,58320212,0.015);
 8     
 9     sa0.deposit(5,5000);
10     sa1.deposit(25,10000);
11     sa0.deposit(45,5500);
12     sa1.withdraw(60,4000);
13     
14     sa0.settle(90);
15     sa1.settle(90);
16     
17     sa0.show();cout<<endl;
18     sa1.show();cout<<endl;
19     cout<<"Total:"<<SavingsAccount::getTotal()<<endl;
20     return 0;
21 }
View Code

 

 改进建议：

可以将四舍五入金额的逻辑封装到一个单独的工具函数中，以促进代码的重用。

考虑使用更具描述性的输出格式。例如，使用一致的格式化输出消息可以提高清晰度。

添加一个专门用于检索当前余额的方法，无需调用 show 方法。

尽可能为不改变类状态的方法添加 const 修饰符。这包括没有产生副作用的 accumulate() 和 getBalance() 方法。

如果您引入常量（如每日利息计算），考虑将它们定义为类常量。

posted @ 2024-10-23 22:42  shorekeeper  阅读(37)  评论(0)  编辑  收藏  举报