实验3 类和对象_基础编程2

任务1：

#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";
}

#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));
}

#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：

问题1：自定义了2个类：window和button。使用3个类：iostream，string和vector。window类和button类之间存在组合关系

问题2：click，display，close，add_button不适合变为const。click,close不适合变为inline。

问题3：构造一个string类型的s,内容是40个“*”用于分割窗口。

 

 

 

 

任务2：

#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：

问题1：第一行创建了一个名为v1，长度为5的vector<int>向量，且全部初始化为42。第二行将v1对象复制给v2。第三行将v1的第一个值改为-999，v1其余值和v2值不变。

问题2：第一行创建了一个名为v1的二维向量，并初始化了两个内部向量。第二行将v1对象复制给v2。第三行在v1第一个向量内插入-999，其余不变。

问题3：第一行将v1内第一个子向量对象复制给t1。第二行输出t1中的最后一个元素。第三行将v2内第一个子向量对象复制给t2。第四行输出t2中的最后一个元素。

问题4：类vector内部封装的复制构造函数实现机制是深复制；是需要提供一个const成员函数作为接口

 

任务3：

#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;
}

#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：

问题1：深复制

问题2：返回值类型变成int而不是int&，不能正确运行。有安全隐患，函数返回值有可能被改变。

问题3：可以，后面的复制操作会变为对象复制，但是仍然能够运行。

 

 

 

 

任务4：

#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
// xxx

Matrix::Matrix(int n, int m) : lines(n), cols(m) {     // 构造一个n*m初始值为0的矩阵
    ptr = new double[n * m];
    for (int i = 0; i < n * m; ++i) {
        ptr[i] = 0;
    }
}

Matrix::Matrix(int n) : lines(n), cols(n) {      // 构造一个n*n初始值为0的矩阵
    ptr = new double[n * n];
    for (int i = 0; i < n * n; ++i) {
        ptr[i] = 0;
    }
}

Matrix::Matrix(const Matrix &x) : lines(x.lines), cols(x.cols) {       // 复制构造函数
    ptr = new double[lines * cols];
    for (int i = 0; i < lines * cols; ++i) {
        ptr[i] = x.ptr[i];
    }
}

Matrix::~Matrix() {                  // 析构函数
    delete[] ptr;
}

void Matrix::set(const double *pvalue) {         // 行为矩阵赋值
    assert(pvalue!= nullptr);
    for (int i = 0; i < lines * cols; ++i) {
        ptr[i] = pvalue[i];
    }
}

void Matrix::clear() {        // 矩阵值置0
    for (int i = 0; i < lines * cols; ++i) {
        ptr[i] = 0;
    }
}

const double& Matrix::at(int i, int j) const {       // 返回矩阵对象索引(i,j)的元素const和非const引用
    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 {          // 返回矩阵对象行列数
    return lines;
}
int Matrix::get_cols() const {
    return cols;
}

void Matrix::display() const {            // 按行显示矩阵对象元素值
    for (int i = 0; i < lines; ++i) {
        for (int j = 0; j < cols; ++j) {
            cout << at(i, j) << " ";
        }
        cout << endl;
    }
}

#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：

 

 

 

任务5：

#ifndef USER_HPP
#define USER_HPP

#include <iostream>
#include <string>

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

public:                      
    User(const std::string& uname)                                 // 构造函数
        : name(uname), password("123456"), email("") {}

    User(const std::string& uname, const std::string& pwd, const std::string& em)
        : name(uname), password(pwd), email(em) {}

    void set_email() {            // 设置邮箱操作 
        std::string input_email;
        while (true) {
            std::cout << "Enter email: ";
            std::cin >> input_email;
            if (input_email.find('@') != std::string::npos) {
                email = input_email;
                break;
            } else {
                std::cout << "Invalid email. Please try again." << std::endl;
            }
        }
    }
 
    void change_password() {          // 修改密码操作 
        std::string old_pwd, new_pwd, confirm_pwd;
        int attempts = 0;

        while (attempts < 3) {
            std::cout << "Enter old password: ";
            std::cin >> old_pwd;
            if (old_pwd == password) {
                break;
            } else {
                attempts++;
                std::cout << "Incorrect password. Try again." << std::endl;
            }
        }

        if (attempts == 3) {
            std::cout << "Too many attempts. Please try again later." << std::endl;
            return;
        }

        while (true) {
            std::cout << "Enter new password: ";
            std::cin >> new_pwd;
            std::cout << "Confirm new password: ";
            std::cin >> confirm_pwd;

            if (new_pwd == confirm_pwd) {
                password = new_pwd;
                break;
            } else {
                std::cout << "Passwords do not match. Please try again." << std::endl;
            }
        }
    }

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

#endif 

#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：

 

 

 

 

 

 

任务6：

#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;
    }
};

#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;
    else
        return DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1];
}
void Date::show()const {
    cout << getYear() << "-" << getMonth() << "-" << getDay();
}

#include"date.h"
#include<string>
class SavingsAccount {
private:
    std::string id;
    double balance;
    double rate;
    Date lastDate;
    double accumulation;
    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;
};

#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 std::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 std::string& msg)const {
    cout << "Error(#" << id << ");" << msg << endl;
}
void SavingsAccount::deposit(const Date& date, double amount, const std::string& desc) {
    record(date, amount, desc);
}
void SavingsAccount::withdraw(const Date& date, double amount, const std::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 << "\tBalance:" << balance;
}

#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), 5000, "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;
}

运行结果：