实验3
任务一
#pragma once #include <iostream> #include <string> using std::string; using std::cout; // °´Å¥Àà 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"; } #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(); } #pragma once #include "button.hpp" #include <vector> #include <iostream> using std::vector; using std::cout; using std::endl; // ´°¿ÚÀà 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)); }
问题一：运用标准库中的vector和string 两个类；组合关系：window类中用Button类，button集合是window类的属性；
问题二：不适合，const修饰的对象是不可以更改的，而inline可以减少函数调用的开销；在小型函数中inline可以提高效率；
问题三：增强输出的可读性，作用是输出40个“*”；
任务二
#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 << "²âتش1:\n"; test1(); cout << "\n²âتش2:\n"; test2(); }
问题一：初始化v1,并且v2复制v1,将v1的42改成-999；
问题二：初始化v1 ；v2为常量复制v1 ；将v1第一行中的最后一个改成-999；
问题三：将v1，v2的第一行元素分别复制给f1,f2，输出这一行最后一个元素;
问题四：进行深复制；
任务三：
#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 << "²âÊÔ1: \n";
test1();
cout << "\n²âÊÔ2: \n";
test2();
}
问题一：深
问题二：不能；报错：左操作数必须为左值；删除const后，可以运行；
问题三：可以改成vectorInt，但是需要额外空间；
任务四
#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
// xMatrix::Matrix(const Matrix &x): lines{x.get_lines()}, cols{x.get_cols()}, ptr{new double[lines*cols]}{ for(int i = 0;i < lines;i++) for(int j = 0;j < cols;j++){ *(ptr+cols*i+j) = x.ptr[cols*i + j]; } }
}
Matrix::Matrix(int n, int m): lines{n}, cols{m}, ptr{new double[lines*cols]} {}
Matrix::Matrix(int n): lines{n}, cols{n}, ptr{new double[lines*cols]} {}
Matrix::~Matrix(){
delete [] ptr;
}
void Matrix::set(const double *pvalue){
for(int i = 0;i < lines;i++){
for(int j = 0;j < cols;j++){
*(ptr+cols*i+j) = *(pvalue+cols*i+j);
}
}
}
void Matrix::clear(){
for(int i = 0;i < lines;i++){
for(int j = 0;j < cols;j++){
*(ptr+cols*i+j) = 0;
}
}
}
const double& Matrix::at(int i, int j) const{
assert(i >= 0 && i < lines && j >= 0 && j < cols);
return *(ptr+cols*i+j);
}
double& Matrix::at(int i, int j){
assert(i >= 0 && i < lines && j >= 0 && j < cols);
return *(ptr+cols*i+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+cols*i+j) << " ";
}
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] = {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();
}
任务五
#pragma once
#include <iostream>
#include <string>
class User {
public:
User(const std::string& username, const std::string& password = "", const std::string& email = "");
void set_email();
void change_password();
void display() const;
private:
std::string username_;
std::string password_;
std::string email_;
};
// 构造函数实现
User::User(const std::string& username, const std::string& password, const std::string& email)
: username_(username), password_(password), email_(email) {}
void User::set_email() {
std::string input_email;
bool has_at_symbol = false;
do {
std::cout << "Enter email for " << username_ << ": ";
std::cin >> input_email;
for (char c : input_email) {
if (c == '@') {
has_at_symbol = true;
break;
}
}
if (!has_at_symbol) {
std::cout << "无效的邮箱" << std::endl;
}
} while (!has_at_symbol);
email_ = input_email;
}
void User::change_password() {
std::string old_password;
int attempts = 0;
while (attempts < 3) {
std::cout << "输入旧密码： " << username_ << ": ";
std::cin >> old_password;
if (old_password == password_) {
std::string new_password;
std::cout << "输入新密码： " << username_ << ": ";
std::cin >> new_password;
password_ = new_password;
break;
}
else {
attempts++;
std::cout << "旧密码错误 " << 3 - attempts << std::endl;
}
}
if (attempts == 3) {
std::cout << "错误多次，稍后再试" << std::endl;
}
}
void User::display() const {
std::string password_display(password_.length(), '*');
std::cout << "Username: " << username_ << ", Password: " << password_display << ", Email: " << email_;
}
#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();
}
任务六：
//account.h
#ifndef __ACCOUNT_H__
#define __ACCOUNT_H__
#include "date.h"
#include <string>
class SavingsAccount {//储蓄账户类
private:
std::string id;//账号
double balance;//余额
double rate;//存款的年利率
Date lastDate;//上次变更余额的时期
double accumulation;//按日累加以和
static double total;//所有账户的总金额
//记录一笔账，date为日期，amount为金额，desc为说明
void record(const Date & date, double amount, const std::string & desc);
//报告错误信息
void error(const std::string & msg) const;
//获得指定日期为止的存款金额按日累增值
double accumulate(const Date & date) const {
return accumulation + balance * date.distance(lastDate);
}
public:
//构造函数
SavingsAccount(const Date & date, const std::string & id, double rate);//获得账号
const std::string & getId() const { return id; } //获得余额
double getBalance() const { return balance; } //获得年利率
double getRate() const { return rate; }
static double getTotal() { return total; }//存入现金
void deposit(const Date & date, double amount, const std::string & desc);//取出现金
void withdraw(const Date & date, double amount, const std::string & desc);//结算利息，每年1月1日调用一次该函数
void settle(const Date & date);
//显示账户信息
void show() const;
};
#endif //__ACCOUNT_H__#pragma once
//date.h
#ifndef __DATE_H__
#define __DATE_H__
class Date {//日期类
private:
int year; //年
int month;//月
int day;//日
int totalDays;//该日期是从公元元年1月1日开始的第几天
public:
Date(int year, int month, int day);//用年、月、日构造日期
int getYear() const { return year; }
int getMonth() const { return month; }
int getDay() const { return day; }
int getMaxDay() const;//获得当月有多少天
bool isLeapYear() const {//判断当年是否为闰年
return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
}
void show() const;//输出当前日期
int distance(const Date & date) const {
return totalDays - date.totalDays;
}
};
#endif //__DATE_H__
//account.cpp
#include "account.h"
#include <cmath>
#include <iostream>
using namespace std;
double SavingsAccount::total = 0;
//SavingsAccount类相关成员函数的实现
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;
//保留小数点后两位
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: " << id << "\tBalance: " << balance;
}
//date.cpp
#include "date.h"
#include <iostream>
#include <cstdlib>
using namespace std;
namespace {
//namespace使下面的定义只在当前文件中有效
const int DAYS_BEFORE_MONTH[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 356 };
}
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();
}
//6.25.cpp
#include "account.h"
#include <iostream>
using namespace std;
int main() {
Date date(2008, 11, 1);
//起始日期
//建立几个账户
SavingsAccount accounts[] = {
SavingsAccount(date, "03755217", 0.015),
SavingsAccount(date, "02342342", 0.015)
};
//几笔账目
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");
//结算所有账户并输出各个账户信息
cout << endl;
for (int i = 0; i < sizeof(accounts) / sizeof(SavingsAccount); i++) {
accounts[i].settle(Date(2009, 1, 1));
accounts[i].show();
cout << endl;
}
cout << "Total: " << SavingsAccount::getTotal() << endl;
return 0;
}
