一、实验目的
加深对类，对象的理解，能够解释类的封装，类的接口
会使用C++语法规则正确定义，实现，测试类，会使用类创建对象，并基于对象编程
针对具体问题场景，练习运用面向对象思维进行设计，合理利用C++语言特性（访问权限控制，static,friend,const)，在数据共享和保护之间达到平衡
会用多文件方式组织代码
加深对C++内存资源管理技术的理解，能够解释构造函数，析构函数的用途，分析它们何时会被调用
二、实验准备
类的抽象，设计
使用C++定义类，使用类创建对象的语法；构造/析构陈洁灵语法，用途及调用时机
类的共享与保护机制：访问权限控制，静态成员（static），友元（friend),const
多文件组织代码
三、实验内容
1. 实验任务1
代码：
t.h
1 #pragma once
2 #include <string>
3
4 class T{
5 public:
6 T(int x = 0, int y = 0);
7 T(const T &t);
8 T(T &&t);
9 ~T();
10 void adjust ( int ratio );
11 void display ( )const ;
12 private:
13 int m1,m2;
14 public:
15 static int get_cnt();
16
17 public:
18 static const std::string doc;
19 static const int max_cnt;
20 private:
21 static int cnt ;
22
23 friend void func();
24
25 };
26 void func();
t.cpp
1 #include"t.h"
2 #include<iostream>
3 #include<string>
4
5 using std::cout;
6 using std::endl;
7 using std::string;
8
9 const std::string T::doc{"a simple class sample"};
10 const int T :: max_cnt= 999;
11 int T::cnt = 0;
12 T ::T (int x,int y) :m1{x},m2{y}
13 {
14 ++cnt;
15 cout << "T constructor called.\n";
16 }
17
18 T ::T (const T &t) :m1{t.m1},m2{t.m2}
19 {
20 ++cnt;
21 cout << "T copy constructor called.\n";
22 }
23
24
25 T ::T(T &&t):m1{t.m1},m2{t.m2}
26 {
27 ++cnt;
28 cout << "T move constructor called.\n";
29 }
30
31 T::~T(){
32 --cnt;
33 cout << "T destructor called.\n";
34
35 }
36 void T::adjust(int ratio){
37 m1*=ratio;
38 m2*=ratio;
39
40 }
41 void T::display ()const
42 {
43 cout<<"("<<m1<<","<<"m2"<<")";
44 }
45
46 int T::get_cnt()
47 {
48 return cnt;
49 }
50
51 void func()
52 {
53 T t5(42);
54 t5.m2=2049;
55 cout << "t5=";t5.display();cout<<endl;
56 }
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 {
11 test();
12 cout<<"\nmain:\n";
13 cout<<"T objects'current count:"<<T::get_cnt()<<endl;
14
15 }
16
17 void test()
18 {
19 cout<<"test class T:\n";
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<<"t3 = ";t4.display();cout<<endl;
36
37 cout<<"T objects'current count: "<<T::get_cnt()<<endl;
38 func();
39 }
运行截图：
问题回答：
问题一：不可以去掉t.h中最后的void func();
friend void func()不可以作为一个完整的函数声明。没有给出函数的参数列表。故还是需要在在t.h最后加上void func();
问题二：构造函数是在对象被创建时利用特定的值构造对象，将对象初始化为一个特定的状态。
普通构造函数是创建一个对象假如有两个参数，就可以接受两个参数，如果没有参数就是使用自定义的默认值，可以是0或者其它。
复制构造函数是一个已经存在的对象创建新的对象的时候调用它，新对象与存在的对象状态相同。
移动构造函数它通过右值引用来实现资源的转移。
调用时机：调用构造函数结束后调用析构函数，析构的顺序与构造的顺序相反。
问题三：
不能正确编译运行
2. 实验任务2
代码:
Complex.h
1 #pragma once
2 #include<string>
3
4 class Complex{
5 //类属性
6 public:
7 static const std::string doc;
8 Complex(double a=0,double b=0);
9 Complex(const Complex &c);
10
11
12 //对象属性
13 private:
14 double real;
15 double imag;
16 //对象方法
17 public:
18 //接口：
19 const double get_real();
20 const double get_imag();
21 Complex add(const Complex& c);
22 //友元函数
23 public:
24 friend Complex add(const Complex &c1,const Complex &c2);
25 friend bool is_equal(const Complex &c1,const Complex &c2);
26 friend bool is_not_equal(const Complex &c1,const Complex &c2);
27 friend void output(const Complex &c);
28 friend double abs(const Complex &c);
29 ~Complex();
30 };
31
32 Complex add(const Complex &c1,const Complex &c2);
33 bool is_equal(const Complex &c1,const Complex &c2);
34 bool is_not_equal(const Complex &c1,const Complex &c2);
35 void output(const Complex &c);
36 double abs(const Complex &c);
Complex.cpp
1 #include"Complex.h"
2 #include<iostream>
3 #include<string>
4 #include<cmath>
5
6
7 using std::cout;
8 using std::endl;
9 using std::string;
10
11
12
13 //类属性
14 const std::string Complex::doc={"a simplified complex class"};
15 Complex::Complex(double a,double b):real(a),imag{b} {};
16 Complex::Complex(const Complex &c){
17 real=c.real;
18 imag=c.imag;
19 }
20 //接口
21 const double Complex::get_real(){
22 return real;
23
24 }
25 const double Complex::get_imag(){
26 return imag;
27 }
28 Complex Complex::add(const Complex& c) {
29 return Complex(real + c.real, imag + c.imag);
30 }
31
32
33 Complex add(const Complex &c1,const Complex &c2){
34 Complex c;
35 c.real=c1.real+c2.real;
36 c.imag=c1.imag+c2.imag;
37 return c;
38
39 }
40 bool is_equal(const Complex &c1,const Complex &c2){
41 if(c1.real==c2.real&&c1.imag==c2.imag)
42 return 1;
43 else
44 return 0;
45 }
46 bool is_not_equal(const Complex &c1,const Complex &c2){
47 if(c1.real!=c2.real||c1.imag!=c2.imag)
48 return 1;
49 else
50 return 0;
51 }
52 void output(const Complex &c){
53 if(c.imag<0)
54 cout<<c.real<<c.imag<<"i";
55 else
56 cout<<c.real<<"+"<<c.imag<<"i";
57 }
58 double abs(const Complex &c){
59 return sqrt(c.real*c.real+c.imag*c.imag);
60 }
61 Complex::~Complex()=default;
运行截图：
3. 实验任务3
代码：
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 }
运行截图：
问题回答：
4. 实验任务4
代码：
Fraction.h
1 #pragma once
2 #include<string>
3
4 class Fraction{
5 public:
6 static const std::string doc;
7 Fraction(int up=1,int down=1);
8 Fraction(const Fraction &c);
9
10 int get_up()const;
11 int get_down() const ;
12 Fraction negative() const;
13 static int gcd(int a,int b);
14 Fraction simplify()const;
15
16 public:
17 //友元函数
18 friend void output(const Fraction &c);
19 friend Fraction add(const Fraction &c1,const Fraction &c2);
20 friend Fraction sub(const Fraction &c1,const Fraction &c2);
21 friend Fraction mul(const Fraction &c1,const Fraction &c2);
22 friend Fraction div(const Fraction &c1,const Fraction &c2);
23 ~Fraction();
24 private:
25 int up;
26 int down;
27
28
29 };
Fraction.cpp
1 #include"Fraction.h"
2 #include<iostream>
3 #include<string>
4 #include<cmath>
5 #include <iomanip>
6
7 using std::cout;
8 using std::endl;
9 using std::string;
10
11
12
13
14 const std::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.\n"};
15 Fraction::Fraction(int a,int b):up(a),down{b} {}
16
17
18 Fraction::Fraction(const Fraction &c):up(c.up),down(c.down){
19 }
20
21 //简化分数
22 Fraction Fraction::simplify()const{
23
24 int divisor=gcd(up,down);
25
26 return Fraction(up/divisor,down/divisor);}
27
28
29 int Fraction::get_up()const{
30 Fraction c1=this->simplify();
31
32
33 return c1.up;
34 }
35
36
37 int Fraction::get_down()const{
38 Fraction c2=this->simplify();
39 return c2.down;
40
41 }
42 Fraction Fraction::negative()const {
43
44 return Fraction(-up,down);
45 }
46
47 int Fraction::gcd(int a,int b){
48
49 while(b!=0){
50 int temp=b;
51 b=a%b;
52 a=temp;
53 }return a;
54
55
56 }
57
58
59 void output(const Fraction &c){
60
61
62 if(c.down==0){cout<<"分母不能为0"; return;
63 }
64 if(c.up==0){cout<<0;return;}
65
66 Fraction c1=c.simplify();
67 if(c1.down==1){cout<<c.up;
68
69 }
70 else{cout<<c1.get_up()<<"/"<<c1.get_down() ;
71 }
72
73 }
74
75
76
77
78
79
80 Fraction add(const Fraction &c1,const Fraction &c2){
81
82 Fraction c3;
83 c3.up=c1.up*c2.down+c2.up*c1.down;
84 c3.down=c1.down*c2.down;
85
86 return c3.simplify();
87
88
89 }
90
91 Fraction sub(const Fraction &c1,const Fraction &c2){
92 Fraction c3;
93 c3.up=c1.up*c2.down-c2.up*c1.down;
94 c3.down=c1.down*c2.down;
95
96 return c3.simplify();
97 }
98
99 Fraction mul(const Fraction &c1,const Fraction &c2){
100 Fraction c3;
101 c3.up=c1.up*c2.up;
102 c3.down=c1.down*c2.down;
103
104 return c3.simplify();
105 }
106
107
108 Fraction div(const Fraction &c1,const Fraction &c2){
109 Fraction c3;
110 c3.up=c1.up*c2.down;
111 c3.down=c1.down*c2.up;
112
113 return c3.simplify();
114 }
115
116 Fraction::~Fraction()=default;
Fraction_test.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 }
运行截图：
5. 实验任务5
代码：
Bank.h
1 #ifndef ACCOUNT_H
2 #define ACCOUNT_H
3
4 class SavingsAccount{
5 private://用户的Id ，平均数，利率，上次存款时间，计算，总和这些数是私有的。
6 int id;
7 double balance;
8 double rate;
9 int lastDate;
10 double accumulation;
11 static double total;
12 void record(int data,double amount);//一个成员函数：用于输出
13 double accumulate(int date)const{return accumulation+balance*(date-lastDate);}
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 }
21 void deposit(int date,double amount);//存
22 void withdraw(int date,double amount);//取
23 void settle(int date);//结算
24 void show()const;
25 };
26 #endif
Bank.cpp
1 #include <iostream>
2 #include "bank.h"
3 #include <cmath>
4
5 using namespace std;
6
7 double SavingsAccount::total = 0;
8
9 SavingsAccount::SavingsAccount(int date, int id, double rate): id(id), balance(0), rate(rate), lastDate(date), accumulation(0) {
10 std::cout << date << "\t#" << id << " is created" << std::endl;
11 }
12 void SavingsAccount::record(int date, double amount) {
13 accumulation = accumulate(date);
14 lastDate = date;
15 amount = floor(amount * 100 + 0.5) / 100; //保留小数点后两位
16 balance += amount;
17 total += amount;
18 std::cout << date << "\t#" << id << "\t" << amount << "\t"<< balance << std::endl;
19 }
20 void SavingsAccount::deposit(int date, double amount) {
21 record(date, amount);
22 }
23 void SavingsAccount::withdraw(int date, double amount) {
24 if (amount > getBalance()) {
25 std::cout << "Error: not enough money" << std::endl;
26 }
27 else {
28 record(date, -amount);
29 }
30 }
31 void SavingsAccount::settle(int date) {
32 double interest = accumulate(date) * rate / 365; //计算年息
33 if (interest != 0)
34 record(date, interest);
35 accumulation = 0;
36 }
37 void SavingsAccount::show() const {
38 std::cout << "#" << id << "\tBalance: " << balance;
39 }
Bank_test.cpp
1 #include "bank.h"
2 #include <iostream>
3 using namespace std;
4 int main() {
5
6 SavingsAccount sa0(1, 21325302, 0.015);
7 SavingsAccount sal(1, 58320212, 0.015);
8
9 sa0.deposit(5, 5000);
10 sal.deposit(25, 10000);
11 sa0.deposit(45, 5500);
12 sal.withdraw(60, 4000);
13
14 sa0.settle(90);
15 sal.settle(90);
16
17 sa0.show();
18 cout << endl;
19 sal.show();
20 cout << endl;
21 cout << "Total: " << SavingsAccount::getTotal() << endl;
22 return 0;
23 }
运行截图：
个人银行账户管理系统使用了SavingsAccout()类封装了相关类的属性以及方法。也有不到位的地方，比如输入日期，钱数，取款数这些数据，要设置确保数据的输入是合理的，部分不能为负数。
标签：std,const,对象,编程,int,Complex,实验,Fraction,include From： https://www.cnblogs.com/andongni51/p/18494271