实验3 类和对象

标签：std const cout 对象 int 实验 using include

实验任务1：

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";
}

View Code

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));
}

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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();
}

View Code

 问题1：自定义了button类和window类；使用了标准库中的string、vector、iostream类；window类与button类存在组合关系

问题2：不适合， 因为它们被调用时候不会改变数据，不需要加const，而且被调用的次数不多，不需要加inline

问题3：定义一个字符串s，它由40个*组成

实验任务2：

 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();
}

View Code

 问题1：先创建了一个名为v1的vector，包含5跟都是42的元素，然后创建一个名为v2的vector，并用v1来将其初始化，最后将v1的第一个元素改成了-999.

问题2：先创建了一个名为v1的二维vector，然后创建了一个名为v2的二维vector，并用v1来初始化，且因为v2前的const所以v2的值不能改变，最后在v1中的第一个元素“1，2，3”后面添加了一个-999.

问题3：创建了一个名为t1的的vector，并用v1的第一个元素来将其初始化，然后输出t1的最后一个元素的值；创建了一个名为t2的vector，并用v2的第一个元素来将其初始化，然后输出t2的最后一个元素的值，并且因为t2前的const所以t2不能被修改

问题4:

1.深复制

2.需要

实验任务3：

vocterInt.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;
}

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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();
}

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 问题1：深复制

问题2：不能，因为int&存储的是一个int类型的数据的地址，允许修改元素值，而int存储的是int类型数据的副本，无法修改原来的元素值；存在安全隐患，因为可能会改变元素的值。

问题3：可以，不过会额外创建一个vectorInt，需要额外的空间。

实验任务4：

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){
    ptr=new double[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 {
    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*cols;i++){
        if((i+1)%cols!=0){
            cout<<ptr[i]<<" ,";
        }else{
            cout<<ptr[i]<<endl;
        }
    }
}

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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();
}

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 实验任务5：

 user.cpp

#pragma once

#include<iostream>
#include<string>
#include<vector>

using std::cin;
using std::cout;
using std::endl;
using std::vector;
using std::string;

class User{
    public:
        User(string a, string b= "123456", string c= "");
        void set_email();
        void change_password();
        void display();

    private:
        string name,email,password;

};

User::User(string a, string b, string c):name {a}, password {b}, email {c} {
}

void User::set_email() {
    cout << "Enter email address: ";
    int a=0;
    string newemail;
    while(!a) {
        cin >> newemail;
        for (char c: newemail) {
            if (c == '@') 
               a=1;  
    }
    if(a==0)
    cout << "illegal email.Please re-enter email: "; 
    else {
    email=newemail;
    cout << "email is set successfully..." << endl;}
}
}


void User::change_password() {
    string t;
    cout << "Enter old password:" << endl;
    int c = 0;
    while(c < 3) {
        cin >> t;
        if(password==t) {
            cout << "Enter new password:" << endl;
        cin >> password;
        cout << "new password is set successfully...";
            break;
        } else {
            cout << "password input error. Please re-enter angain:" << endl;
            cin.clear();
        }
        ++c;
    }

    if(c == 3) {
        cout << "password input error. Please try after a while.";
    } 
}


void User::display() {
    cout << "name: " << name << endl;
    cout << "pass: ";
    for(int i = 0; i < password.size(); i++) {
        cout << "*";
    }
    cout << endl;
    cout << "eamil: " << email << endl;
}

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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", "[email protected]");
    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();
}

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 实验任务6：

date.h

#ifndef __DATE_H__
#define __DATE_H__
class Date {
    private:
        int year,month,day,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_H__

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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();
}

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 account.h

#ifndef __ACCOUNT_H__
#define __ACCOUNT_H__
#include "date.h"
#include <string>
class SavingsAccount {

    private:
        std::string id;
        double balance,rate,accumulation;
        Date lastDate;
        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

View Code

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//计算年息
                      / 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;
}

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task6.cpp

#include "account.h"
#include <iostream>
using namespace std;
int main() {
    //起始日期
    Date date(2008, 11, 1);
    //建立几个账户
    SavingsAccount accounts[] = {
        SavingsAccount(date,"03755217",0.015),
        SavingsAccount(date, "02342342", 0.015)
    };
    const int n = sizeof(accounts) / sizeof(SavingsAccount); //账户总数

    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;
}

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标签：std,const,cout,对象,int,实验,using,include
From： https://www.cnblogs.com/phanoto/p/18536504