OOP实验三

任务1：

源码：

#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";
}

#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();
}

 

结果：

 回答：

问题1：这个模拟简单GUI的示例代码中，自定义了几个类？使用到了标准库的哪几个类？，

哪些类和类之间存在组合关系？

两个类，

vector，

button类是vector中的元素，该vector是window类的成员。

问题2：在自定义类Button和Window中，有些成员函数定义时加了const, 有些设置成了

inline。如果你是类的设计者，目前那些没有加const或没有设置成inline的，适合添加const，

适合设置成inline吗？你的思考依据是？

Button::click和Window::close不适合加inline,在实际项目中该函数运行的内容较复杂，不必添加const，因为没有数据的传输。

Window::add不适合加inline，需要更改对象内容。

问题3：类Window的定义中，有这样一行代码，其功能是？

窗口分隔线。

任务2：

源码：

 

#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 << "    1:\n";
    test1();

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

 

结果：

 答：

问题1：测试1模块中，这三行代码的功能分别是？

构造大小为5，元素值为42的vector对象。

利用v1复制构造v2。

将v1的第一个值改为-999.

问题2：测试2模块中，这三行代码的功能分别是？

构造以vector对象为元素的vector对象。

利用v1复制构造v2。

获取v1中的第一个vector对象元素，并在该对象末尾增加元素-999。

问题3：测试2模块中，这四行代码的功能分别是？

将v1中第一个元素值付给t1的第一个元素。

输出t1的最后一个元素值。

将v2中第一个元素值付给t2的第一个元素。

输出t2的最后一个元素值。

问题4：根据执行结果，反向分析、推断：

① 标准库模板类vector内部封装的复制构造函数，其实现机制是深复制还是浅复制？

深复制

② 模板类vector的接口at(), 是否至少需要提供一个const成员函数作为接口？

 是

任务3：

源码：

 

#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();
}

结果：

 答：

问题1：vectorInt类中，复制构造函数（line14)的实现，是深复制还是浅复制？

深复制

问题2：vectorInt类中，这两个at()接口，如果返回值类型改成int而非int&（相应地，实现部

分也同步修改），测试代码还能正确运行吗？

能

如果把line18返回值类型前面的const掉，针对

这个测试代码，是否有潜在安全隐患？尝试分析说明。

有，内部元素值会被修改。

问题3：vectorInt类中，assign()接口，返回值类型可以改成vectorInt吗？你的结论，及，原

因分析。

不能，增加了拷贝开销。

任务4：

源码：

 

#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 = (double*)malloc(sizeof(double) * n * m);
}
Matrix::Matrix(int n) {
    lines = n;
    cols = n;
    ptr = (double*)malloc(sizeof(double) * n * n);
}
Matrix::Matrix(const Matrix& x) {
    lines = x.get_lines();
    cols = x.get_cols();
    ptr = (double*)malloc(sizeof(double) * lines * cols);
    int i, j;
    int line = x.get_lines();
    int col = x.get_cols();
    for (i = 0; i < line; i++) {
        for (j = 0; j < col; j++) {
            *(ptr + cols * i + j) = *(x.ptr + cols * i + j);
        }
    }
}
Matrix::~Matrix() {

}
int Matrix::get_lines() const {
    return lines;
}
int Matrix::get_cols()const {
    return cols;
}
void Matrix::set(const double* pvalue) {
    int i, j;
    int line = get_lines();
    int col = get_cols();
    for (i = 0; i < line; i++) {
        for (j = 0; j < col; j++) {
            *(ptr + cols * i + j) = *(pvalue + cols * i + j);
        }
    }
}
void Matrix::clear() {
    int i, j;
    int line = get_lines();
    int col = get_cols();
    for (i = 0; i < line; i++) {
        for (j = 0; j < col; j++) {
            *(ptr + cols * i + j) = 0;
        }
    }
}
const double& Matrix::at(int i, int j) const {
    return *(ptr + cols * i + j);
}
double& Matrix::at(int i, int j) {
    return *(ptr + cols * i + j);
}
void Matrix::display() const {
    int i, j;
    int line = get_lines();
    int col = get_cols();
    for (i = 0; i < line; i++) {
        for (j = 0; j < col; j++) {
            cout << *(ptr + cols * i + j);
            if (j != col - 1) {
                cout << ",";
            }
        }
        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] = {11, 12, 13, 14, 15, 16, 17, 18, 19};

    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();
}

 

结果：

 

任务5：

源码：

 

#include <iostream>
#include <vector>
#include <string>
using namespace std;
class User {
private:
    string name;
    string password;
    string email;
public:
    User(string n);
    User(string n, string pw, string em);
    ~User();
    void set_email();
    void change_password();
    void display()const;
};
User::User(string n){
    name = n;
    password = "123456";
    email = "";
}
User::User(string n, string pw, string em) {
    name = n;
    password = pw;
    email = em;
}
User::~User() {}
void User::set_email() {
    cout << "Enter email address:";
    string em;
    while (1) {
        cin >> em;
        if (em.find('@') == -1) {
            cout << "illegal email.Please re-enter email:";
            continue;
        }
        email = em;
        cout << "email is set successfully." << endl;
        break;
    }
}
void User::change_password() {
    cout << "Enter old password:";
    string opw;
    int cnt = 0;
    while (1) {
        cin >> opw;
        if (opw.compare(password)) {
            cnt++;
            if (cnt >= 3) {
                cout << "Try again later." << endl;
                break;
            }
            cout << "Wrong.Please enter the true old password:";
            continue;
        }
        cout << "Enter new password:";
        cin >> password;
        cout << "new password is set successfully." << endl;
        break;
    }
}
void User::display()const {
    cout << "name:" << name << endl;
    int i;
    cout << "pass:";
    for (i = 0; i < password.size(); i++) {
        cout << '*';
    }
    cout << endl;
    cout << "email:" << email << endl << endl;
}



#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();
}

 

结果：

 

任务6：

源码：

 

#ifndef _ _ACCOUNT_H_ _
#define _ _ACCOUNT_H_ _
#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;
};
#endif //_ _ACCOUNT_H_ _

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"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
        / 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"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"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;
}

 

结果：