实验3 类和对象 基础编程

实验一

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();
}

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));
}

实验结果

问题一：自定义了一个窗口类和一个按钮类，运用了标准库的输入输出类，容器类，string类；容器类和输入输出类在自定义类有组合关系。

问题二：const 是只能调用而不能修改，inline是内联函数，可以对一些简单函数多次重复调用时使用。所以对于尚未设置的函数，观察是否值得保护还是会多次重复调用而来决定选择哪个

问题三：这行代码，可以输出一行40个*作为分割线

实验二

#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();
}

结果

问题一：第21行代码是输出5个42，第22行是为了为了后续输出v2和v1一致，第23行是为了改变v1中第一个为-999

问题二：第32行代码是输出v1为二维数组，第33行是为了后续v2和v1输出一致，第34行是为了加第一行最后一个为-999

问题三：39行是复制输出v1到t1上的，40行是输出t1上的东西，42行是将constv2赋值到t2，43行是输出t2

问题四：是深复制，不需要

实验三

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();
}

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;
}

实验结果

问题一：是浅复制

问题二：能正常运行，可能有风险，对返回的对象进行修改

问题三：返回引用类型的话可以提高效率，并且避免歧义

实验四

tesk.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();
}

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;
};

Matrix:: Matrix (int n, int m){
    lines=n;cols=m;ptr= new double[n*m];
}
 Matrix::  Matrix(int n){
       lines=cols=n; ptr= new double[n*n];
   }
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]);
    } 
}   
 void Matrix:: clear(){
     *ptr=NULL;
     }
 
 Matrix::~Matrix(){
     delete[] ptr;
 }
void  Matrix:: set(const double *pvalue){
    for(int i=0;i<lines*cols;++i){
    *(ptr+i)=*(ptr+i);
    }     
 }
 const double& Matrix::at(int i, int j) const{
     return *(ptr+i*cols+j);
 }
 double& Matrix::at(int i, int j){
     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++){
             std::cout<<*(ptr+i*cols+j)<<",";
         }
         std::cout<<"endl";
     }
 }
 
 

实验结果

实验五

test.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();
}

user.hpp

#pragma once

#include <iostream>
#include <cassert>
#include<string>

using std::cout;
using std::endl;
class User{
    private:
        string name;
        string password;
        string email;
    public:
        User (string a){
        name=a;
        password=123456;
        email=NULL;        
        }
        User(string a,string b,string c){
            name=a;
            password=b;
            email=c;
        }
    User::set_email(){
        string a;
        std::cout<<"Enter email adress";
        std::cout<<endl;
        std::cin>> a ;
        if(a.find('@')!=-1 ){
            std::cout<<"email is set successfully...";
            email=a;
            break;
        }else{
            std::cout<<"illegal email.please re-enter email";
                
        }
    }
    User::change_password(){
        string b;
        std::cout<<"Enter old password";
        std::cin>> b;
            if(b==password){
                break;
            }else{
                std::cout<<"password input error.Please re-enter again:    ";        
                std::cin>>b;
                }if(b==password){
                    break;
                }else{
                       std::cout<<"password input error.Please re-enter again:"    ;                  
                       std::cin>>b;                                
                       }if(b!=password){
                            std::cout<<"password input error.Please try after a while";
                       }
            
    User::display(){
        stirng c(password.size(),"*") 
        std::cout<<"email:  "<<email<<endl;
        std::cout<<"password:   "<<c<<endl;
        std::cout<<"name:  "<<name<<endl;        
    }    
    
    
};

实验结果：

实验六

date.h

#ifndef __DATE_H__
#define __DATE_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;
}
};
#endif

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

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.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");
    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;
}

test.cpp

#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;
}

实验结果