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实验3

时间：2024-11-10 21:07:41浏览次数：1  
标签：std const string int void 实验 cout

Test1:

#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();
}

Q1、定义了两个类，使用了标准库的3个类，Window 类和 Button 类之间存在组合关系

Q2、

Button 类

  1. void click();
    • 不适合添加const：并没有修改button类的任何对象，不需要对其进行保护
    • 不适合设置为inline：click函数虽然简短，但涉及到I/O操作，这是inline函数通常不处理的复杂操作。

Window 类

  1. void display() const;
    • 可以考虑设置为inline：display函数遍历按钮并输出信息，这是一个读取操作且没有复杂的逻辑。如果这个函数在多个地方被频繁调用，将其设置为inline可能会减少函数调用的开销。然而，需要注意的是，如果Window对象很大或display函数被调用的次数不多，inline可能并不会带来显著的性能提升。
  2. void close();
    • 不适合添加const：调用了Button对象的非const成员函数
    • 不适合设置为inline：close函数虽然简短，但它调用了另一个对象的成员函数，并且涉及到I/O操作
  3. void add_button(const string &label);
    • 不适合添加const：add_button函数添加了一个新的Button对象
    • 可以考虑设置为inline：如果add_button函数被频繁调用，并且Window对象不是很大，将其设置为inline可能会减少函数调用的开销

Q3、创建了一个string类型的对象s，使用40个字符'*'来初始化。这个字符串将用作窗口显示时的边框。

Test2:

#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();
 }

Q1、创建了一个名为v1的vector<int>对象，长度为5，且全部初始化为42；

将v1对象复制给v2，且为深拷贝不可修改；

v1的第一个元素改为-999，其他元素的值不变，v2中的所有元素值都不变；

Q2、创建了一个名为v1的二维向量，并通过列表初始化为其赋了两个内部向量，{1, 2, 3},和{4, 5, 6, 7}；

创建了一个名为v2的常量二维向量，并用v1作为参数去初始化它，是一个深拷贝，v2内部的值不可被修改；

修改了v1的第一个向量，用push_back向内部添加了一个新元素-999.此时v1的第一个向量变成{1，2，3，-999}，而v2不变

Q3、提取了v1的第一个内部向量，将其内容复制给了新的一维向量t1，t1是可独立修改的一维向量；

输出了 t1 中的最后一个元素；

从 v2 中提取了第一个内部向量，并将其内容复制到了新的常量一维向量 t2 中，t2不能被修改；

输出了 t2 中的最后一个元素；

 

Test3:

 victorint.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 << "测试2: \n";
    test2();
}

Q1、深复制

Q2、不能；出现左边返回一个常数无法被修改

Q3、可以，只是后面的复制操作变为对象复制，仍然能够运行

 

Test4:

 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 *value);         // 用value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) {
    ptr = new double[n*m];
    clear();
}
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 *value) {
    for(int i=0;i<lines*cols;i++)
        ptr[i] = value[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 << endl;
    }
}

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();
}

 

 

Test5:

 user.hpp

#include <iostream>
#include <string>

using namespace std;

class User {
    public:
        User(string name, string email="", string password="123456"):name(name), email(email), password(password) {}
        void set_email();
        void change_password();
        void display();

    private:
        string name;
        string email;
        string password;


};
void User::set_email()
{
    string new_email;
    while(1){
        cout << "Enter new email: ";
        cin>>new_email;
        if(new_email.find("@") == string::npos || new_email.find(".") == string::npos){
            cout << "Invalid email format. Please try again.\n";
        }
        else{
            email = new_email;
            cout<<"Email is set successfully.\n";
            break;
        }
    }

}

void User::change_password()
{
    string new_password;
    string old_password;
    for(int i=0; i<3; i++)
    {
        cout<<"Enter old password: ";
        cin>>old_password;
        if(password == old_password)
        {
            cout<<"Enter new password: ";
            cin>>new_password;
            password = new_password;
            cout<<"Password changed successfully.\n";
            return;
        }
        else
        {
            cout<<"Incorrect password. Please try again.\n";
        }
    }
    cout<<"Too many incorrect attempts. Account locked.\n";
}

void User::display()
{
    cout<<"Name: "<<name<<"\n";
    cout<<"Password: "<<string(password.size(), '*')<<"\n";
    cout<<"Email: "<<email<<"\n";

}

task5.hpp

#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();
}

user.cpp

#include <iostream>
#include <string>

class User {
public:
    // 构造函数
    User(const std::string& name, const std::string& password = "123456", const std::string& email = "");
    
    // 设置邮箱
    void set_email();
    
    // 修改密码
    void change_password();
    
    // 显示用户信息
    void display();

private:
    std::string name;   // 用户名
    std::string password; // 密码
    std::string email;   // 邮箱
};

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

// 设置邮箱
void User::set_email() {
    std::string input;
    std::cout << "Enter email for " << name << ": ";
    std::cin.ignore(); // 忽略之前读取的换行符
    std::getline(std::cin, input);
    while (input.find('@') == std::string::npos) {
        std::cout << "Invalid email. Please enter a valid email: ";
        std::getline(std::cin, input);
    }
    email = input;
}

// 修改密码
void User::change_password() {
    std::string old_password, new_password, confirm_password;
    std::cout << "Enter old password: ";
    std::cin.ignore();
    std::getline(std::cin, old_password);
    int attempts = 0;
    while (old_password != password && attempts < 3) {
        std::cout << "Incorrect password. Try again: ";
        std::getline(std::cin, old_password);
        attempts++;
    }
    if (attempts == 3) {
        std::cout << "Too many failed attempts. Exiting password change." << std::endl;
        return;
    }
    std::cout << "Enter new password: ";
    std::getline(std::cin, new_password);
    std::cout << "Confirm new password: ";
    std::getline(std::cin, confirm_password);
    if (new_password == confirm_password) {
        password = new_password;
    } else {
        std::cout << "Passwords do not match. Password change cancelled." << std::endl;
    }
}

// 显示用户信息
void User::display() {
    std::cout << "Username: " << name << ", Password: " << std::string(password.size(), '*') << ", Email: " << email << std::endl;
}

 

Test6:

date.h

#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;
    }
};

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

#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;
};

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 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;
}

task6

#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;
}

 

标签：std,const,string,int,void,实验,cout
From： https://www.cnblogs.com/karis/p/18529010

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