实验三 类与对象

#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();
}

测试结果：

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？

答：自定义了两个类。使用了string和vector标准库中的函数，两个类。window和button存在组合关系。

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？陈述你的答案和理由。

答：我觉得无需再加。const用于函数中是为了不改变类中数据成员的值，inline定义内联函数。在上述代码中，没有大段重复且逻辑简单的操作，没必要加inline。而const，上述代码中会对类的数据成员进行修改，所以也不用加。

问题3：类Window的定义中，有这样一行代码，其功能是？

答：调用string类的构造函数，一行元素全为“*”的字符串

 

2、实验任务二

task2

#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();
}

 

测试结果：

问题1：测试1模块中，这三行代码的功能分别是？

答：构造v1，长度为5，值为42。构造v2传入形参v1。将v1第一个值改成-999。

问题2：测试2模块中，这三行代码的功能分别是？

答：初始化v1。v2复制v1，而v2不可被修改。将v1末尾添加-999

问题3：测试2模块中，这四行代码的功能分别是

答：定义t1为v1的第0行，输出t1的最后一个数；t2同理。

问题4：1、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？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

答：1、深复制。2、需要

 

3、实验任务三

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();
}

测试结果截图：

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

答：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？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

答：不能正常运行会报错，存在安全隐患。

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。

答：不能。返回值类型不对。

 

4、实验任务四

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);           // 构造函数，构造一个n*m的矩阵, 初始值为valueMatrix(int n);                  // 构造函数，构造一个n*n的矩阵, 初始值为valueMatrix(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0const 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
// xxxdouble value;
Matrix::Matrix(int n, int m) :lines{ n }, cols{ m } {ptr = new double[n * m];for (int i = 0;i < n * m;i++) {ptr[i] = value;}
}
Matrix::Matrix(int n) : Matrix(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;}
}
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×mm1.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×nm2.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();
}

测试结果：

 

5、实验任务五

User.hpp

#pragma once
#include<iostream>
#include<cassert>
#include<string>
using namespace std;
class User{private:string name,password,email;public:User (string n,string p="123456",string e="");void set_email();void change_password();void display();};
User::User(string n,string p,string e):name(n),password(p),email(e){}
void User::set_email(){string input;bool vaild = false;do{cout<<"请输入邮箱：";cin>>input;if(input.find('@')){email=input;vaild=true;} elsecout<<"输入有误"<<endl;}while(!vaild);
}void User::change_password()
{int trycount=0;string oldpassword;do{if(trycount>=3){cout<<"用户稍后再试"<<endl;     }cout<<"请输入旧密码：";cin>>oldpassword;trycount++;}while(oldpassword!=password);string newpassword;cout<<"请输入新密码：";cin>>newpassword;password=newpassword;}
void User::display()
{string printpassword;for(int i=0;i<password.length();i++)printpassword+='*';cout<<"用户名："<<name<<"密码："<<printpassword<<"邮箱："<<email<<endl;}

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();
}

 测试结果：

 6、实验任务六

#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;
}

account.cpp

#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");elserecord(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;
}

account.h

#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_ _

data.cpp

#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();
}

data.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;}
};

运行结果：