实验3
任务1：
button.hpp:
1 #pragma once 2 3 #include<iostream> 4 #include<string> 5 6 using std::string; 7 using std::cout; 8 9 class Button{ 10 public: 11 Button(const string &text); 12 string get_label() const; 13 void click(); 14 15 private: 16 string label; 17 }; 18 19 Button::Button(const string &text):label{text}{ 20 } 21 22 inline string Button::get_label() const{ 23 return label; 24 } 25 26 void Button::click(){ 27 cout << "Button '" << label << "' clicked\n"; 28 }
window.hpp:
1 #include "button.hpp" 2 3 #include<iostream> 4 #include<vector> 5 6 using std::vector; 7 using std::cout; 8 using std::endl; 9 10 class window{ 11 public: 12 window(const string &win_title); 13 void display() const; 14 void close(); 15 void add_button(const string &label); 16 17 private: 18 string title; 19 vector<Button> buttons; 20 }; 21 22 window::window(const string &win_title):title{win_title}{ 23 buttons.push_back(Button("close")); 24 } 25 26 inline void window::display() const{ 27 string s(40,'*'); 28 29 cout << s <<endl; 30 cout << "window title: " << title << endl; 31 cout << "It has " << buttons.size() << " buttons: " << endl; 32 for(const auto &i:buttons) 33 cout << i.get_label() << " button" <<endl; 34 cout << s <<endl; 35 } 36 37 void window::close(){ 38 cout << "close window '"<< title << "'" <<endl; 39 buttons.at(0).click(); 40 } 41 42 void window::add_button(const string &label){ 43 buttons.push_back(Button(label)); 44 }
task1.cpp:
1 #include "window.hpp" 2 3 #include<iostream> 4 5 using std::cout; 6 using std::cin; 7 8 void test(){ 9 window w1("new window"); 10 w1.add_button("maximize"); 11 w1.display(); 12 w1.close(); 13 } 14 15 int main(){ 16 cout << "用组合类模拟简单GUI：\n"; 17 test(); 18 }
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：button类和window类；用到了iostream类、string类、vector类；
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？你的思考依据是？
答：不适合。const不可更改数据元素，而inline可以提高执行效率。
问题3：类Window的定义中，有这样一行代码，其功能是？
答：连续输出40个“*”号
任务2：
1 #include<iostream> 2 #include<vector> 3 4 using namespace std; 5 6 void output1(const vector<int> &v) { 7 for(auto &i:v) 8 cout << i << ", "; 9 cout << "\b\b \n"; 10 } 11 12 void output2(const vector<vector<int>> v) { 13 for(auto &i:v) { 14 for(auto &j:i) 15 cout << j <<", "; 16 cout << "\b\b \n"; 17 } 18 } 19 20 void test1() { 21 vector<int> v1(5,42); 22 const vector<int> v2(v1); 23 24 v1.at(0) = -999; 25 cout << "v1: "; 26 output1(v1); 27 cout << "v2: "; 28 output1(v2); 29 cout << "v1.at(0) = " << v1.at(0) << endl; 30 cout << "v2.at(0) = " << v2.at(0) << endl; 31 } 32 void test2() { 33 vector<vector<int>> v1 {{1, 2, 3}, {4, 5, 6, 7}}; 34 const vector<vector<int>> v2(v1); 35 v1.at(0).push_back(-999); 36 cout << "v1: \n"; 37 output2(v1); 38 cout << "v2: \n"; 39 output2(v2); 40 vector<int> t1 = v1.at(0); 41 cout << t1.at(t1.size()-1) << endl; 42 const vector<int> t2 = v2.at(0); 43 cout << t2.at(t2.size()-1) << endl; 44 } 45 int main() { 46 cout << "测试1:\n"; 47 test1(); 48 cout << "\n测试2:\n"; 49 test2(); 50 }
结果：
问题1：
vector<int> v1(5, 42); 创建一个含5个元素均为42的vector对象v1；
const vector<int> v2(v1);创建一个vector对象v2，初始值为v1；
v1.at(0) = -999; v1中索引为0的元素赋值为-999；
问题2：
vector<vector<int>> v1{{1, 2, 3}, {4, 5, 6, 7}}; 创建一个vector类对象，包含{1, 2, 3}和{4, 5, 6, 7}；
const vector<vector<int>> v2(v1);创建一个vector类对象v2，初始值为v1；
v1.at(0).push_back(-999); 在v1中索引为0的子vecto后面添加一个元素，它的值是-999
问题3：
vector<int> t1 = v1.at(0); 创建一个vector类对象t1，赋值为v1索引为0的子vector；
cout << t1.at(t1.size()-1) << endl; 输出t1的最后一个元素；
const vector<int> t2 = v2.at(0); 创建一个vector类对象t2，赋值为v2的索引为0的子vector；
cout << t2.at(t2.size()-1) << endl; 输出t2的最后一个元素
问题4：
（1）是深复制，因为v1和v2改变数据互不影响
（2）需要。
任务3：
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
1 #include "vectorInt.hpp" 2 #include <iostream> 3 using std::cin; 4 using std::cout; 5 void output(const vectorInt &vi) { 6 for(auto i = 0; i < vi.get_size(); ++i) 7 cout << vi.at(i) << ", "; 8 cout << "\b\b \n"; 9 } 10 void test1() { 11 int n; 12 cout << "Enter n: "; 13 cin >> n; 14 vectorInt x1(n); 15 for(auto i = 0; i < n; ++i) 16 x1.at(i) = i*i; 17 cout << "x1: "; 18 output(x1); 19 vectorInt x2(n, 42); 20 vectorInt x3(x2); 21 x2.at(0) = -999; 22 cout << "x2: "; 23 output(x2); 24 cout << "x3: "; 25 output(x3); 26 } 27 void test2() { 28 const vectorInt x(5, 42); 29 vectorInt y(10, 0); 30 cout << "y: "; 31 output(y); 32 y.assign(x); 33 cout << "y: "; 34 output(y); 35 cout << "x.at(0) = " << x.at(0) << endl; 36 cout << "y.at(0) = " << y.at(0) << endl; 37 } 38 int main() { 39 cout << "测试1: \n"; 40 test1(); 41 cout << "\n测试2: \n"; 42 test2(); 43 }
结果：
问题1：深复制；
问题2：不能；存在安全隐患，此时返回值可被修改
问题3：可以，因为此时是深复制
任务4：
matrix.hpp
1 #pragma once 2 #include <iostream> 3 #include <cassert> 4 using std::cout; 5 using std::endl; 6 // 类Matrix的声明 7 class Matrix { 8 public: 9 Matrix(int n, int m); // 构造函数，构造一个n*m的矩阵, 初始值为value 10 Matrix(int n); // 构造函数，构造一个n*n的矩阵, 初始值为value 11 Matrix(const Matrix &x); // 复制构造函数， 使用已有的矩阵X构造 12 ~Matrix(); 13 void set(const double *pvalue); // 用pvalue指向的连续内存块数据按行为矩阵赋值 14 void clear(); // 把矩阵对象的值置0 15 const double& at(int i, int j) const; // 返回矩阵对象索引(i,j)的元素const引用 16 double& at(int i, int j); // 返回矩阵对象索引(i,j)的元素引用 17 int get_lines() const; // 返回矩阵对象行数 18 int get_cols() const; // 返回矩阵对象列数 19 void display() const; 20 private: 21 int lines; // 矩阵对象内元素行数 22 int cols; // 矩阵对象内元素列数 23 double *ptr; 24 }; 25 // 类Matrix的实现：待补足 26 Matrix::Matrix(int n,int m):lines {n},cols {m} { 27 ptr = new double[n*m]; 28 } 29 Matrix::Matrix(int n) :lines { n }, cols { n } { 30 ptr = new double[n * n]; 31 } 32 Matrix::Matrix(const Matrix& x) :lines { x.lines }, cols {x.cols} { 33 ptr = new double[lines * cols]; 34 for (int i = 0; i < lines * cols; i++) ptr[i] = x.ptr[i]; 35 } 36 Matrix::~Matrix() { 37 delete[] ptr; 38 } 39 void Matrix::set(const double* pvalue) { 40 for (int i = 0; i < lines * cols; i++) 41 ptr[i] = pvalue[i]; 42 } 43 void Matrix::clear() { 44 for (int i = 0; i < lines * cols; i++) 45 ptr[i] = 0; 46 } 47 const double& Matrix::at(int i, int j) const { 48 assert(i >= 0 && i < lines && j >= 0 && j < cols); 49 return ptr[i * cols + j]; 50 } 51 double& Matrix::at(int i, int j) { 52 assert(i >= 0 && i < lines && j >= 0 && j < cols); 53 return ptr[i * cols + j]; 54 } 55 int Matrix::get_lines()const { 56 return lines; 57 } 58 int Matrix::get_cols()const { 59 return cols; 60 } 61 void Matrix::display() const { 62 for (int i = 0; i < lines; i++) { 63 for (int j = 0; j < cols; j++) 64 cout << ptr[i * cols + j] << ", "; 65 cout << "\b\b \n"; 66 } 67 } 68 // xxx
task4.cpp
1 #include "matrix.hpp" 2 #include <iostream> 3 #include <cassert> 4 using std::cin; 5 using std::cout; 6 using std::endl; 7 const int N = 1000; 8 // 输出矩阵对象索引为index所在行的所有元素 9 void output(const Matrix &m, int index) { 10 assert(index >= 0 && index < m.get_lines()); 11 for(auto j = 0; j < m.get_cols(); ++j) 12 cout << m.at(index, j) << ", "; 13 cout << "\b\b \n"; 14 } 15 void test1() { 16 double x[1000] = {1, 2, 3, 4, 5, 6, 7, 8, 9}; 17 int n, m; 18 cout << "Enter n and m: "; 19 cin >> n >> m; 20 Matrix m1(n, m); // 创建矩阵对象m1, 大小n×m 21 m1.set(x); // 用一维数组x的值按行为矩阵m1赋值 22 Matrix m2(m, n); // 创建矩阵对象m1, 大小m×n 23 m2.set(x); // 用一维数组x的值按行为矩阵m1赋值 24 Matrix m3(2); // 创建一个2×2矩阵对象 25 m3.set(x); // 用一维数组x的值按行为矩阵m4赋值 26 cout << "矩阵对象m1: \n"; 27 m1.display(); 28 cout << endl; 29 cout << "矩阵对象m2: \n"; 30 m2.display(); 31 cout << endl; 32 cout << "矩阵对象m3: \n"; 33 m3.display(); 34 cout << endl; 35 } 36 void test2() { 37 Matrix m1(2, 3); 38 m1.clear(); 39 const Matrix m2(m1); 40 m1.at(0, 0) = -999; 41 cout << "m1.at(0, 0) = " << m1.at(0, 0) << endl; 42 cout << "m2.at(0, 0) = " << m2.at(0, 0) << endl; 43 cout << "矩阵对象m1第0行: "; 44 output(m1, 0); 45 cout << "矩阵对象m2第0行: "; 46 output(m2, 0); 47 } 48 int main() { 49 cout << "测试1: \n"; 50 test1(); 51 cout << "测试2: \n"; 52 test2(); 53 }
结果：
任务5：
User.hpp
1 #pragma once 2 3 #include<iostream> 4 #include<cassert> 5 #include<string> 6 #include<vector> 7 8 using namespace std; 9 10 class User { 11 public: 12 User(string username, string password = "123456", string userEmail = ""); 13 ~User(); 14 15 void set_email(); 16 void change_password(); 17 void display(); 18 19 20 21 22 private: 23 string name; 24 string email; 25 string password; 26 27 }; 28 29 User::User(string username, string password, string userEmail):name {username}, password {password}, email {userEmail} { 30 } 31 32 User::~User() { 33 } 34 void User::set_email() { 35 cout << "Enter email address: "; 36 while(1) { 37 string useremail; 38 cin >> useremail; 39 size_t pos = email.find('@'); 40 if (pos != string::npos) { 41 email = useremail; 42 cout << "email is set successfully..." << endl; 43 break; 44 } else { 45 cout << "illegal email.Please re-enter email: "; 46 } 47 } 48 } 49 50 51 52 void User::change_password() { 53 string t; 54 cout << "Enter old password:" << endl; 55 int c = 0; 56 while(c < 3) { 57 cin >> t; 58 if(t.compare(password) == 0) { 59 break; 60 } else { 61 cout << "password input error. Please re-enter angain:" << endl; 62 cin.clear(); 63 } 64 ++c; 65 } 66 67 if(c == 3) { 68 cout << "password input error. Please try after a while."; 69 } else { 70 cout << "Enter new password:" << endl; 71 cin >> password; 72 cout << "new password is set successfully..."; 73 } 74 } 75 76 77 void User::display() { 78 cout << "name: " << name << endl; 79 cout << "pass: "; 80 for(int i = 0; i < password.size(); i++) { 81 cout << "*"; 82 } 83 cout << endl; 84 cout << "eamil: " << email << endl; 85 }
task5.cpp
1 #include "user.hpp" 2 #include <iostream> 3 #include <vector> 4 #include <string> 5 using std::cin; 6 using std::cout; 7 using std::endl; 8 using std::vector; 9 using std::string; 10 void test() { 11 vector<User> user_lst; 12 13 User u1("Alice", "2024113", "Alice@hotmail.com"); 14 user_lst.push_back(u1); 15 cout << endl; 16 17 User u2("Bob"); 18 u2.set_email(); 19 u2.change_password(); 20 user_lst.push_back(u2); 21 cout << endl; 22 23 User u3("Hellen"); 24 u3.set_email(); 25 u3.change_password(); 26 user_lst.push_back(u3); 27 cout << endl; 28 29 cout << "There are " << user_lst.size() << " users. they are: " << endl; 30 for(auto &i: user_lst) { 31 i.display(); 32 cout << endl; 33 } 34 } 35 int main() { 36 test(); 37 }
结果：
任务6：
account.h
1 #ifndef __ACCOUNT_H__ 2 #define __ACCOUNT_H__ 3 #include "date.h" 4 #include <string> 5 class SavingsAccount { 6 7 private: 8 std::string id; 9 double balance,rate,accumulation; 10 Date lastDate; 11 static double total; 12 13 void record(const Date& date, double amount, const std::string& desc); 14 15 void error(const std::string& msg) const; 16 17 double accumulate(const Date& date) const { 18 return accumulation + balance * date.distance(lastDate); 19 } 20 public: 21 SavingsAccount(const Date& date, const std::string& id, double rate); 22 const std::string& getId() const { 23 return id; 24 } 25 double getBalance() const { 26 return balance; 27 } 28 double getRate() const { 29 return rate; 30 } 31 static double getTotal() { 32 return total; 33 } 34 35 void deposit(const Date& date, double amount, const std::string& desc); 36 37 void withdraw(const Date& date, double amount, const std::string& desc); 38 39 void settle(const Date& date); 40 41 void show() const; 42 }; 43 #endif
account.cpp
1 #include "account.h" 2 #include <cmath> 3 #include <iostream> 4 using namespace std; 5 double SavingsAccount::total = 0; 6 SavingsAccount::SavingsAccount(const Date& date, const string& id, double rate) :id(id), balance(0), rate(rate), lastDate(date), accumulation(0) { 7 date.show(); 8 cout << "\t#" << id << "created" << endl; 9 } 10 void SavingsAccount::record(const Date& date, double amount, const string& desc) { 11 accumulation = accumulate(date); 12 lastDate = date; 13 amount = floor(amount * 100 + 0.5) / 100; 14 balance += amount; 15 total += amount; 16 date.show(); 17 cout << "t\#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl; 18 } 19 void SavingsAccount::error(const string& msg) const { 20 cout << "Error(# " << id << " ):" << msg << endl; 21 } 22 void SavingsAccount::deposit(const Date & date, double amount, const string & desc) { 23 record(date, amount, desc); 24 } 25 void SavingsAccount::withdraw(const Date & date, double amount, const string& desc) { 26 if (amount > getBalance()) 27 error("not enough money"); 28 else 29 record(date, -amount, desc); 30 } 31 void SavingsAccount::settle(const Date& date) { 32 double interest = accumulate(date) * rate//计算年息 33 / date.distance(Date(date.getYear() - 1, 1, 1)); 34 if (interest != 0) 35 record(date, interest, "interest"); 36 accumulation = 0; 37 } 38 void SavingsAccount::show() const { 39 cout << id << "\tBalance:" << balance; 40 }
date.h
1 #ifndef __DATE_H__ 2 #define __DATE_H__ 3 class Date { 4 private: 5 int year,month,day,totalDays; 6 public: 7 Date(int year,int month,int day); 8 int getYear()const { 9 return year; 10 } 11 int getMonth()const { 12 return month; 13 } 14 int getDay() const { 15 return day; 16 } 17 int getMaxDay() const; 18 bool isLeapYear()const { 19 return year%4==0 && year%100!=0 ||year%400==0; 20 } 21 void show()const; 22 int distance(const Date &date)const { 23 return totalDays-date.totalDays; 24 } 25 26 }; 27 #endif / / _DATE_H__
date.cpp
1 #include "date.h" 2 #include <iostream> 3 #include <cstdlib> 4 using namespace std; 5 namespace { 6 const int DAYS_BEFORE_MONTH[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }; 7 } 8 Date::Date(int year, int month, int day) : year(year), month(month), day(day) { 9 if (day <= 0 || day > getMaxDay()) { 10 cout << "Invalid date:"; 11 show(); 12 cout << endl; 13 exit(1); 14 } 15 int years = year - 1; 16 totalDays = years * 365 + years / 4 - years / 100 + years / 400 + DAYS_BEFORE_MONTH[month - 1] + day; 17 if (isLeapYear() && month > 2) totalDays++; 18 } 19 int Date::getMaxDay()const { 20 if (isLeapYear() && month == 2) 21 return 29; 22 else 23 return DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1]; 24 } 25 void Date::show() const { 26 cout << getYear() << " - " << getMonth() << " - " << getDay(); 27 }
task6.cpp
1 #include "account.h" 2 #include <iostream> 3 using namespace std; 4 int main() { 5 //起始日期 6 Date date(2008, 11, 1); 7 //建立几个账户 8 SavingsAccount accounts[] = { 9 SavingsAccount(date,"03755217",0.015), 10 SavingsAccount(date, "02342342", 0.015) 11 }; 12 const int n = sizeof(accounts) / sizeof(SavingsAccount); //账户总数 13 14 accounts[0].deposit(Date(2008, 11, 5), 5000, "salary"); 15 accounts[1].deposit(Date(2008, 11, 25), 10000, "sell stock 0323"); 16 17 accounts[0].deposit(Date(2008, 12, 5), 5500, "salary"); 18 accounts[1].withdraw(Date(2008, 12, 20), 4000, "buy a laptop"); 19 20 cout << endl; 21 for (int i = 0; i < n; i++) { 22 accounts[i].settle(Date(2009, 1, 1)); 23 accounts[i].show(); 24 cout << endl; 25 } 26 cout << "Total: " << SavingsAccount::getTotal() << endl; 27 return 0; 28 }
结果：
