实验3 类与对象

实验任务1：

botton.hpp代码：

#pragma once

#include <iostream>
#include <string>

using std::string;
using std::cout;

// 按钮类
class Button {
public:
    Button(const string &text);
    string get_label() const;
    void click();

private:
    string label;
};

Button::Button(const string &text): label{text} {
}

inline string Button::get_label() const {
    return label;
}

void Button::click() {
    cout << "Button '" << label << "' clicked\n";
}

window.hpp代码:

#pragma once
#include "button.hpp"
#include <vector>
#include <iostream>

using std::vector;
using std::cout;
using std::endl;

// 窗口类
class Window{
public:
    Window(const string &win_title);
    void display() const;
    void close();
    void add_button(const string &label);

private:
    string title;
    vector<Button> buttons;
};

Window::Window(const string &win_title): title{win_title} {
    buttons.push_back(Button("close"));
}

inline void Window::display() const {
    string s(40, '*');

    cout << s << endl;
    cout << "window title: " << title << endl;
    cout << "It has " << buttons.size() << " buttons: " << endl;
    for(const auto &i: buttons)
        cout << i.get_label() << " button" << endl;
    cout << s << endl;
}

void Window::close() {
    cout << "close window '" << title << "'" << endl;
    buttons.at(0).click();
}

void Window::add_button(const string &label) {
    buttons.push_back(Button(label));
}

task1.cpp代码：

#include "window.hpp"
#include <iostream>

using std::cout;
using std::cin;

void test() {
    Window w1("new window");
    w1.add_button("maximize");
    w1.display();
    w1.close();
}

int main() {
    cout << "用组合类模拟简单GUI:\n";
    test();
}

运行结果截图：

 问题1：

自定义了两个类Botton 类和Window类

标准库类：使用iostream类、string类、vector类

Button类代表一个按钮，具有显示标签和点击的功能；Window类代表一个窗口，可以包含多个按钮，Window类中包含Button类的对象，用于表示窗口中的按钮。

 

问题2：

构造函数不需要 const，因为构造函数会修改对象的状态，初始化成员变量和添加初始按钮。不需要 inline，构造函数通常不适合内联。

click() display() close() add_button不需要 const，函数会输出信息并触发其他状态变化。不需要 inline，函数包含 I/O 操作和容器访问，不适合内联。

 

问题3：

调用window中的成员函数display时，通过字符串s显示四十个'*'分割界面。

 

实验任务2：

test2代码：

#include <iostream>
#include <vector>

using namespace std;

void output1(const vector<int> &v) {
    for(auto &i: v)
        cout << i << ", ";
    cout << "\b\b \n";
}

void output2(const vector<vector<int>> v) {
    for(auto &i: v) {
        for(auto &j: i)
            cout << j << ", ";
        cout << "\b\b \n";
    }
}

void test1() {
    vector<int> v1(5, 42);
    const vector<int> v2(v1);

    v1.at(0) = -999;
    cout << "v1: ";  output1(v1);
    cout << "v2: ";  output1(v2);
    cout << "v1.at(0) = " << v1.at(0) << endl;
    cout << "v2.at(0) = " << v2.at(0) << endl;
}

void test2() {
    vector<vector<int>> v1{{1, 2, 3}, {4, 5, 6, 7}};
    const vector<vector<int>> v2(v1);

    v1.at(0).push_back(-999);
    cout << "v1: \n";  output2(v1);
    cout << "v2: \n";  output2(v2);

    vector<int> t1 = v1.at(0);
    cout << t1.at(t1.size()-1) << endl;
    
    const vector<int> t2 = v2.at(0);
    cout << t2.at(t2.size()-1) << endl;
}

int main() {
    cout << "测试1:\n";
    test1();

    cout << "\n测试2:\n";
    test2();
}

运行截图：

 

问题1:

 vector<int> 类型的向量 v1，并用值 42 初始化了它的5个元素。

常量向量 v2，它是 v1 的拷贝。由于 v2 是常量，其内容不可修改。

修改 v1 的第一个元素为 -999。

 

问题2：

vector 类型的向量 v1，并初始化为包含两个子向量的向量。

常量向量 v2，它是 v1 的拷贝。由于 v2 是常量，所以不可修改。

向 v1 的第一个子向量添加元素 -999。

 

问题3：

获取v1里的第一个子向量赋值给t1

输出t1的最后一个元素-999，验证-999已经被添加

获取v2里的第一个子向量赋值给t2

输出t2的最后一个元素3

 

问题4：

标准库模板类vector的复制函数使用深复制，不需要至少提供一个const成员函数作为接口。

 

实验任务3：

task3代码：

#include "vectorInt.hpp"
#include <iostream>

using std::cin;
using std::cout;

void output(const vectorInt &vi) {
    for(auto i = 0; i < vi.get_size(); ++i)
        cout << vi.at(i) << ", ";
    cout << "\b\b \n";
}


void test1() {
    int n;
    cout << "Enter n: ";
    cin >> n;

    vectorInt x1(n);
    for(auto i = 0; i < n; ++i)
        x1.at(i) = i*i;
    cout << "x1: ";  output(x1);

    vectorInt x2(n, 42);
    vectorInt x3(x2);
    x2.at(0) = -999;
    cout << "x2: ";  output(x2);
    cout << "x3: ";  output(x3);
}

void test2() {
    const vectorInt  x(5, 42);
    vectorInt y(10, 0);

    cout << "y: ";  output(y);
    y.assign(x);
    cout << "y: ";  output(y);
    
    cout << "x.at(0) = " << x.at(0) << endl;
    cout << "y.at(0) = " << y.at(0) << endl;
}

int main() {
    cout << "测试1: \n";
    test1();

    cout << "\n测试2: \n";
    test2();
}

运行截图：

问题1：

深复制

问题2：

不能正常运行，返回值类型是常数且不可以被修改

会存在安全隐患，可以通过返回值修改数据，破坏函数的封装性和数据的完整性。

 

问题3：
 可以，但会存在额外的内存开销，因为存在复制。

 

实验任务4：

matrix.cpp代码：

#pragma once

#include <iostream>
#include <cassert>

using std::cout;
using std::endl;

// 类Matrix的声明
class Matrix {
public:
    Matrix(int n, int m);           // 构造函数，构造一个n*m的矩阵, 初始值为value
    Matrix(int n);                  // 构造函数，构造一个n*n的矩阵, 初始值为value
    Matrix(const Matrix &x);        // 复制构造函数， 使用已有的矩阵X构造
    ~Matrix();

    void set(const double *pvalue);         // 用pvalue指向的连续内存块数据按行为矩阵赋值
    void clear();                           // 把矩阵对象的值置0
    
    const double& at(int i, int j) const;   // 返回矩阵对象索引(i,j)的元素const引用
    double& at(int i, int j);               // 返回矩阵对象索引(i,j)的元素引用
    
    int get_lines() const;                  // 返回矩阵对象行数
    int get_cols() const;                   // 返回矩阵对象列数

    void display() const;                    // 按行显示矩阵对象元素值

private:
    int lines;      // 矩阵对象内元素行数
    int cols;       // 矩阵对象内元素列数
    double *ptr;
};
 
// 类Matrix的实现：待补足
Matrix::Matrix(int n,int m):lines(n),cols(m),ptr(new double[n*m]()){}
 
 Matrix::Matrix(int n):lines(n),cols(n),ptr(new double[n*n]()){}
 
 Matrix::Matrix(const Matrix &x):lines(x.lines),cols(x.cols),ptr(new double[lines*cols]()){
     for(int i=0;i<lines*cols;i++)
     ptr[i]=x.ptr[i];
 }
 
 Matrix::~Matrix(){
     delete[] ptr;
 }
 
 void Matrix::set(const double *pvalue){
     for(int i=0;i<lines*cols;i++)
     ptr[i]=pvalue[i];
 }
 
 void Matrix::clear(){
     for(int i=0;i<lines*cols;i++)
     ptr[i]=0.0;
 }
 
 const double& Matrix::at(int i,int j) const
 {
     assert(i>=0&&i<lines&&j>=0&&j<cols);
     return ptr[i*cols+j];
 }
 
 double &Matrix::at(int i,int j)
 {
     assert(i>=0&&i<lines&&j>=0&&j<cols);
     return ptr[i*cols+j];
 }
 
 int Matrix::get_lines() const{
     return lines;
 }
 
 int Matrix::get_cols() const{
     return cols;
 }
 
 void Matrix::display() const{
      for(int i=0;i<lines;i++){
         for(int j=0;j<cols;j++){
            cout<<at(i,j)<<" ";
        }
        cout<<endl;
    }
 }
Matrix.hpp

tesk4代码：

#include "matrix.hpp"
#include <iostream>
#include <cassert>

using std::cin;
using std::cout;
using std::endl;


const int N = 1000;

// 输出矩阵对象索引为index所在行的所有元素
void output(const Matrix &m, int index) {
    assert(index >= 0 && index < m.get_lines());

    for(auto j = 0; j < m.get_cols(); ++j)
        cout << m.at(index, j) << ", ";
    cout << "\b\b \n";
}


void test1() {
    double x[1000] = {1, 2, 3, 4, 5, 6, 7, 8, 9};

    int n, m;
    cout << "Enter n and m: ";
    cin >> n >> m;

    Matrix m1(n, m);    // 创建矩阵对象m1, 大小n×m
    m1.set(x);          // 用一维数组x的值按行为矩阵m1赋值

    Matrix m2(m, n);    // 创建矩阵对象m1, 大小m×n
    m2.set(x);          // 用一维数组x的值按行为矩阵m1赋值

    Matrix m3(2);       // 创建一个2×2矩阵对象
    m3.set(x);          // 用一维数组x的值按行为矩阵m4赋值

    cout << "矩阵对象m1: \n";   m1.display();  cout << endl;
    cout << "矩阵对象m2: \n";   m2.display();  cout << endl;
    cout << "矩阵对象m3: \n";   m3.display();  cout << endl;
}

void test2() {
    Matrix m1(2, 3);
    m1.clear();
    
    const Matrix m2(m1);
    m1.at(0, 0) = -999;

    cout << "m1.at(0, 0) = " << m1.at(0, 0) << endl;
    cout << "m2.at(0, 0) = " << m2.at(0, 0) << endl;
    cout << "矩阵对象m1第0行: "; output(m1, 0);
    cout << "矩阵对象m2第0行: "; output(m2, 0);
}

int main() {
    cout << "测试1: \n";
    test1();

    cout << "测试2: \n";
    test2();
}

运行截图：

 

实验任务5：

user.cpp代码：

#include<bits/stdc++.h>
using namespace std;
class User{
    private:
        string name;
        string password;
        string email;

    public:
        User(const string &name,const string &password="123456", const string &email=""):name(name),password(password),email(email){}
    void set_email(){
        string _email;
        int tag=0;
        cout<<"Enter email address: ";
        while(tag==0){
            cin>>_email;
            int len=sizeof(_email);
            for(int i=0;i<len;i++){
                if(_email[i]=='@')
                  tag=1;
            }
            if(tag)
                cout<< "email is set successfully..."<<endl;
            else
                cout<<"illegal email. Please re-enter email:";
        }

    }

    void change_password(){
        int attempt=3;
        string old_password , new_password;
        cout<<"Enter old password: ";
        while(attempt>0){
            attempt--;
            cin>>old_password;
            if(old_password==password){
                cout<<"Enter new password: ";
                cin>>new_password;
                password=new_password;
                cout<<"new password is set successfully..."<<endl;
                return ;
            }
            else{
                cout<<"password input error. Please re-enter again: ";
            }
        }
        cout<<"password input error. Please try after a while. "<<endl;
    }

    void display() const {
        cout<<"name:   "<<name<<endl;
        cout<<"pass:   ";
        int length=sizeof(password);
        for(int i=1;i<=length;i++)
          cout<<"*";
        cout<<endl;
        cout<<"email:   "<<email<<endl;
    }
};

tesk5:

#include "user.hpp"
#include <iostream>
#include <vector>
#include <string>

using std::cin;
using std::cout;
using std::endl;
using std::vector;
using std::string;

void test() {
    vector<User> user_lst;

    User u1("Alice", "2024113", "Alice@hotmail.com");
    user_lst.push_back(u1);
    cout << endl;

    User u2("Bob");
    u2.set_email();
    u2.change_password();
    user_lst.push_back(u2);
    cout << endl;

    User u3("Hellen");
    u3.set_email();
    u3.change_password();
    user_lst.push_back(u3);
    cout << endl;

    cout << "There are " << user_lst.size() << " users. they are: " << endl;
    for(auto &i: user_lst) {
        i.display();
        cout << endl;
    }
}

int main() {
    test();
}

运行结果截图：

 

实验任务6：

 data.h代码：

#pragma once
 class Date{        
 private:
    int year;        
    int month;        
    int day;    
    int totalDays;
  public:    
      Date(int year, int month, int day) ;
     int getYear() const {return year;}
     int getMonth() const {return month;}
     int getDay() const {return day;}
     int getMaxDay() const;     
     bool isLeapYear() const {
         return year%4==0 &&year%100 !=0 || year%400==0;
     }
 void show() const;
 int distance(const Date& date) const {
 return totalDays-date.totalDays;
 }
 }; 
date.h

 

data.cpp代码：

#include "date.h"
#include <iostream>
#include <cstdlib>
using namespace std;
namespace {const int DAYS_BEFORE_MONTH[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
}
Date::Date(int year, int month, int day) : year(year), month(month), day(day) {if (day <= 0 || day > getMaxDay()) {cout << "Invalid date:";show();cout << endl;exit(1);}int years = year - 1;totalDays = years * 365 + years / 4 - years / 100 + years / 400 + DAYS_BEFORE_MONTH[month - 1] + day;if (isLeapYear() && month > 2) totalDays++;
}
int Date::getMaxDay()const {if (isLeapYear() && month == 2)return 29;elsereturn DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1];
}
void Date::show() const {cout << getYear() << " - " << getMonth() << " - " << getDay();
}

accout.h代码：

#ifndef __ACCOUNT_H__
#define __ACCOUNT_H__
#include "date.h"
#include <string>
class SavingsAccount {

    private:
        std::string id;
        double balance,rate,accumulation;
        Date lastDate;
        static double total;

        void record(const Date& date, double amount, const std::string& desc);

        void error(const std::string& msg) const;

        double accumulate(const Date& date) const {
            return accumulation + balance * date.distance(lastDate);
        }
    public:
        SavingsAccount(const Date& date, const std::string& id, double rate);
        const std::string& getId() const {
            return id;
        }
        double getBalance() const {
            return balance;
        }
        double getRate() const {
            return rate;
        }
        static double getTotal() {
            return total;
        }

        void deposit(const Date& date, double amount, const std::string& desc);

        void withdraw(const Date& date, double amount, const std::string& desc);

        void settle(const Date& date);

        void show() const;
};
#endif

accout.cpp代码：

#include "account.h"
#include <cmath>
#include <iostream>
using namespace std;
double SavingsAccount::total = 0;
SavingsAccount::SavingsAccount(const Date& date, const string& id, double rate) :id(id), balance(0), rate(rate), lastDate(date), accumulation(0) {
    date.show();
    cout << "\t#" << id << "created" << endl;
}
void SavingsAccount::record(const Date& date, double amount, const string& desc) {
    accumulation = accumulate(date);
    lastDate = date;
    amount = floor(amount * 100 + 0.5) / 100;
    balance += amount;
    total += amount;
    date.show();
    cout << "t\#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
}
void SavingsAccount::error(const string& msg) const {
    cout << "Error(# " << id << " ): " << msg << endl;
}
void SavingsAccount::deposit(const Date & date, double amount, const string & desc) {
    record(date, amount, desc);
}
void SavingsAccount::withdraw(const Date & date, double amount, const string& desc) {
    if (amount > getBalance())
        error("not enough money");
    else
        record(date, -amount, desc);
}
void SavingsAccount::settle(const Date& date) {
    double interest = accumulate(date) * rate//计算年息
                      / date.distance(Date(date.getYear() - 1, 1, 1));
    if (interest != 0)
        record(date, interest, "interest");
    accumulation = 0;
}
void SavingsAccount::show() const {
    cout << "ID: "<< id << "\tBalance:" << balance;
}

6_25.cpp代码：

#include "account.h"
#include <iostream>
using namespace std;
int main() {

    Date date(2008, 11, 1);
    SavingsAccount accounts[] = {
        SavingsAccount(date,"03755217",0.015),
        SavingsAccount(date, "02342342", 0.015)
    };
    const int n = sizeof(accounts) / sizeof(SavingsAccount); 

    accounts[0].deposit(Date(2008, 11, 5), 5000, "salary");
    accounts[1].deposit(Date(2008, 11, 25), 10000, "sell stock 0323");

    accounts[0].deposit(Date(2008, 12, 5), 5500, "salary");
    accounts[1].withdraw(Date(2008, 12, 20), 4000, "buy a laptop");

    cout << endl;
    for (int i = 0; i < n; i++) {
        accounts[i].settle(Date(2009, 1, 1));
        accounts[i].show();
        cout << endl;
    }
    cout << "Total: " << SavingsAccount::getTotal() << endl;
    return 0;
}

运行截图：