实验3 类和对象_基础编程2

 任务一

源代码 button.hpp

#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

#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

#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：

问题一：自定义了两个类Button和Window,运用了标准库的类：vector、cout、string。Window类中包含了一个 vector<Button> 类型的成员变量buttons,因此Window类和Button类之间存在组合关系。

问题二：Button类中void click()修改了标准输出，不能改为const或设置为inline。Window类中void add_button(const string &label)可以设置为inline，其构造函数为简单函数。

问题三：string s(40, '*');  输出40个“*”符号作为分隔线。

 

任务二

task2.cpp

#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();
}

运行结果截图：

问题一：

问题二：

问题三：

问题四：
1.是深复制，新对象和原对象拥有独立的内存空间。

2.需要。const函数允许在常量对象上调用，并且保证不会修改对象的任何成员变量。

 

任务三

vectorInt.hpp

#pragma once

#include <iostream>
#include <cassert>

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

// 动态int数组对象类
class vectorInt{
public:
    vectorInt(int n);
    vectorInt(int n, int value);
    vectorInt(const vectorInt &vi);
    ~vectorInt();

    int& at(int index);
    const int& at(int index) const;

    vectorInt& assign(const vectorInt &v);
    int get_size() const;

private:
    int size;
    int *ptr;       // ptr指向包含size个int的数组
};

vectorInt::vectorInt(int n): size{n}, ptr{new int[size]} {
}

vectorInt::vectorInt(int n, int value): size{n}, ptr{new int[size]} {
    for(auto i = 0; i < size; ++i)
        ptr[i] = value;
}

vectorInt::vectorInt(const vectorInt &vi): size{vi.size}, ptr{new int[size]} {
    for(auto i = 0; i < size; ++i)
        ptr[i] = vi.ptr[i];
}

vectorInt::~vectorInt() {
    delete [] ptr;
}

const int& vectorInt::at(int index) const {
    assert(index >= 0 && index < size);

    return ptr[index];
}

int& vectorInt::at(int index) {
    assert(index >= 0 && index < size);

    return ptr[index];
}

vectorInt& vectorInt::assign(const vectorInt &v) {  
    delete[] ptr;       // 释放对象中ptr原来指向的资源

    size = v.size;
    ptr = new int[size];

    for(int i = 0; i < size; ++i)
        ptr[i] = v.ptr[i];

    return *this;
}

int vectorInt::get_size() const {
    return size;
}

task3.cpp

#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();
}

运行结果截图

问题1：深复制

问题2：不能将返回值类型改成int而非int&，由于at()现在返回的是值，因此无法通过返回的值来修改原始容器中的元素。

如果把line18返回值类型前面的const删掉，则不能修改任何成员变量。

问题3：不能。assign()返回值而不是引用,无法连续调用多个返回引用的成员函数。

 

任务四

matrix.hpp

#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, double value = 0); // 构造函数，构造一个n*m的矩阵, 初始值为value 
    Matrix(int n, double value = 0); // 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

Matrix::Matrix(int n, int m, double value) 
    : lines(n), cols(m), ptr(new double[n * m]) {
    for (int i = 0; i < n * m; ++i) {
        ptr[i] = value;
    }
}

Matrix::Matrix(int n, double value) 
    : Matrix(n, n, value) {}

Matrix::Matrix(const Matrix &x) 
    : lines(x.lines), cols(x.cols), ptr(new double[x.lines * x.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;
    }
}

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 << ptr[i * cols + j] << ", ";
        }
        cout << "\b\b \n";
    }
}

task4.cpp

#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();
}

运行结果截图

 

任务五

user.hpp

#ifndef USER_HPP
#define USER_HPP

#include <iostream>
#include <string>

class User {
private:
    std::string name;
    std::string password;
    std::string email;

    bool is_valid_email(const std::string& email) {
        return email.find('@') != std::string::npos;
    }

public:
    // 默认构造函数，使用默认密码和邮箱
    User(const std::string& user_name)
        : name(user_name), password("123456"), email("") {}

    // 完整构造函数
    User(const std::string& user_name, const std::string& user_password, const std::string& user_email)
        : name(user_name), password(user_password), email(user_email) {}

    // 设置邮箱
    void set_email() {
        std::string input_email;
        int attempts = 0;
        while (true) {
            std::cout << "Enter email address: ";
            std::cin >> input_email;
            if (is_valid_email(input_email)) {
                email = input_email;
                std::cout << "email is set successfully..." << std::endl;
                break;
            } else {
                std::cout << "illegal email. Please re-enter email: ";
                attempts++;
            }
            if (attempts >= 3) {
                std::cout << "Too many invalid attempts. Please try again later." << std::endl;
                break;
            }
        }
    }

    // 修改密码
    void change_password() {
        std::string old_password, new_password;
        int attempts = 0;
        while (true) {
            std::cout << "Enter old password: ";
            std::cin >> old_password;
            if (old_password == password) {
                break;
            } else {
                std::cout << "password input error. Please re-enter again: ";
                attempts++;
            }
            if (attempts >= 3) {
                std::cout << "password input error. Please try after a while." << std::endl;
                return;
            }
        }

        std::cout << "Enter new password: ";
        std::cin >> new_password;
        password = new_password;
        std::cout << "new password is set successfully..." << std::endl;
    }

    // 显示用户信息
    void display() const {
        std::cout << "name:   " << name << std::endl;
        std::cout << "pass:   ";
        for (char c : password) {
            std::cout << '*';
        }
        std::cout << std::endl;
        std::cout << "email:  " << email << std::endl;
    }
};

#endif // USER_HPP

task5.cpp

#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

 

 

任务六

date.h

#ifndef __DATE_H__
#define __DATE_H__
 class Date {//日期类
private:
         int year; //年
         int month;//月
         int day;//日
         int totalDays;//该日期是从公元元年1月1日开始的第几天
 public:
         Date(int year, int month, int day);//用年、月、日构造日期
         int getYear() const { return year; }
         int getMonth() const { return month; }
         int getDay() const { return day; }
         int getMaxDay() const;//获得当月有多少天
         bool isLeapYear() const {//判断当年是否为闰年
                     return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
    }
     void show() const;//输出当前日期
         int distance(const Date & date) const {
        return totalDays - date.totalDays;
    }
};
 #endif //__DATE_H__

date.cpp 

//date.cpp
#include "date.h"
#include <iostream>
#include <cstdlib>
using namespace std;
namespace {
    //namespace使下面的定义只在当前文件中有效
        const int DAYS_BEFORE_MONTH[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 356 };
}
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;
    else return DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1];
}
void Date::show() const {
    cout << getYear() << "-" << getMonth() << "-" << getDay();
}

account.h

//account.h
#ifndef __ACCOUNT_H__
#define __ACCOUNT_H__
#include "date.h"
#include <string>
class SavingsAccount {//储蓄账户类
 private:
    std::string id;//账号
        double balance;//余额
        double rate;//存款的年利率
        Date lastDate;//上次变更余额的时期
        double accumulation;//按日累加以和
        static double total;//所有账户的总金额
             //记录一笔账，date为日期，amount为金额，desc为说明
        void record(const Date & date, double amount, const std::string & desc);
    //报告错误信息
        void error(const std::string & msg) const;
    //获得指定日期为止的存款金额按日累增值
        double accumulate(const Date & date) const {
        return accumulation + balance * date.distance(lastDate);
    }
public:
    //构造函数
        SavingsAccount(const Date & date, const std::string & id, double rate);//获得账号
        const std::string & getId() const { return id; } //获得余额
        double getBalance() const { return balance; } //获得年利率
        double getRate() const { return rate; }
    static double getTotal() { return total; }//存入现金
 void deposit(const Date & date, double amount, const std::string & desc);//取出现金
        void withdraw(const Date & date, double amount, const std::string & desc);//结算利息，每年1月1日调用一次该函数
        void settle(const Date & date);
        //显示账户信息
        void show() const;
};
#endif //__ACCOUNT_H__#pragma once

account.cpp

//account.cpp
#include "account.h"
#include <cmath>
#include <iostream>
using namespace std;
double SavingsAccount::total = 0;
//SavingsAccount类相关成员函数的实现
 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;
    //保留小数点后两位
        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 / 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;
}

 task6.cpp

//6.25.cpp
#include "account.h"
#include <iostream>
using namespace std;
int main() {
    Date date(2008, 11, 1);
    //起始日期
        //建立几个账户
        SavingsAccount accounts[] = {
       SavingsAccount(date, "03755217", 0.015),
       SavingsAccount(date, "02342342", 0.015)
     };
    //几笔账目
        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");
    //结算所有账户并输出各个账户信息
        cout << endl;
    for (int i = 0; i < sizeof(accounts) / sizeof(SavingsAccount); i++) {
        accounts[i].settle(Date(2009, 1, 1));
        accounts[i].show();
        cout << endl;
    }
    cout << "Total: " << SavingsAccount::getTotal() << endl;
    return 0;
}

运行结果截图