实验3
task1.cpp
1 #pragma once 2 3 #include <iostream> 4 #include <string> 5 6 using std::string; 7 using std::cout; 8 9 // 按钮类 10 class Button { 11 public: 12 Button(const string& text); 13 string get_label() const; 14 void click(); 15 16 private: 17 string label; 18 }; 19 20 Button::Button(const string& text) : label{ text } { 21 } 22 23 inline string Button::get_label() const { 24 return label; 25 } 26 27 void Button::click() { 28 cout << "Button '" << label << "' clicked\n"; 29 }
1 #pragma once 2 #include "button.hpp" 3 #include <vector> 4 #include <iostream> 5 6 using std::vector; 7 using std::cout; 8 using std::endl; 9 10 // 窗口类 11 class Window{ 12 public: 13 Window(const string &win_title); 14 void display() const; 15 void close(); 16 void add_button(const string &label); 17 18 private: 19 string title; 20 vector<Button> buttons; 21 }; 22 23 Window::Window(const string &win_title): title{win_title} { 24 buttons.push_back(Button("close")); 25 } 26 27 inline void Window::display() const { 28 string s(40, '*'); 29 30 cout << s << endl; 31 cout << "window title: " << title << endl; 32 cout << "It has " << buttons.size() << " buttons: " << endl; 33 for(const auto &i: buttons) 34 cout << i.get_label() << " button" << endl; 35 cout << s << endl; 36 } 37 38 void Window::close() { 39 cout << "close window '" << title << "'" << endl; 40 buttons.at(0).click(); 41 } 42 43 void Window::add_button(const string &label) { 44 buttons.push_back(Button(label)); 45 }
1 #include "window.hpp" 2 #include <iostream> 3 4 using std::cout; 5 using std::cin; 6 7 void test() { 8 Window w1("new window"); 9 w1.add_button("maximize"); 10 w1.display(); 11 w1.close(); 12 } 13 14 int main() { 15 cout << "用组合类模拟简单GUI:\n"; 16 test(); 17 }
问题1：自定义了两个类，分别是Window和Button。使用了标准库中的iostream、string、vector类。Window和Button之间存在组合关系。
问题2：click适合设置成inline，inline函数小，设置成内联可以减少跳转。
问题3：创建了一个长度为 40 的字符串，其中每个位置都被字符 '*' 填充。结果是一个包含 40 个星号的字符串。
运行结果截图：
task2.cpp
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 v1.at(0) = -999; 24 cout << "v1: "; output1(v1); 25 cout << "v2: "; output1(v2); 26 cout << "v1.at(0) = " << v1.at(0) << endl; 27 cout << "v2.at(0) = " << v2.at(0) << endl; 28 } 29 30 void test2() { 31 vector<vector<int>> v1{ {1, 2, 3}, {4, 5, 6, 7} }; 32 const vector<vector<int>> v2(v1); 33 v1.at(0).push_back(-999); 34 cout << "v1: \n"; output2(v1); 35 cout << "v2: \n"; output2(v2); 36 vector<int> t1 = v1.at(0); 37 cout << t1.at(t1.size() - 1) << endl; 38 const vector<int> t2 = v2.at(0); 39 cout << t2.at(t2.size() - 1) << endl; 40 } 41 int main() { 42 cout << "测试1:\n"; 43 test1(); 44 cout << "\n测试2:\n"; 45 test2(); 46 }
问题1：v1是一个包含5个元素的可变大小数组，每个元素的值都是42。v2通过复制构造函数用v1的内容来初始化它。由于v2被声明为const，它的内容在创建后就不能被修改。v3使用at成员函数来访问v1中的第一个元素，并将其值更改为-999。
问题2：v1是一个二维向量，包含两个元素：第一个元素是一个包含1, 2, 3的vector<int>，第二个元素是一个包含4, 5, 6, 7的vector<int>。v2是由v1初始化的不可修改的对象。这行代码通过at成员函数访问v1中的第一个元素，并调用push_back成员函数添加一个值为-999的新元素。
问题3：
vector<int> t1 = v1.at(0);这行代码从v1中获取索引为0的vector<int>元素{1，2，3，-999}，并将其复制到一个新的对象t1中。
cout << t1.at(t1.size() - 1) << endl;这行代码使用at成员函数访问t1中的最后一个元素，这行代码将输出-999。
const vector<int> t2 = v2.at(0);这行代码从v2中获取索引为0的元素，并将其复制到一个新的常量vector<int>对象t2中。由于v2是const的，并且它是通过复制v1的初始状态来创建的，所以t2是{1, 2, 3}。
cout << t2.at(t2.size() - 1) << endl;这行代码输出3；
问题4：①深复制 ②需要提供一个const成员函数作为接口。
运行结果截图：
task3.cpp
1 #pragma once 2 3 #include <iostream> 4 #include <cassert> 5 6 using std::cout; 7 using std::endl; 8 9 // 动态int数组对象类 10 class vectorInt{ 11 public: 12 vectorInt(int n); 13 vectorInt(int n, int value); 14 vectorInt(const vectorInt &vi); 15 ~vectorInt(); 16 17 int& at(int index); 18 const int& at(int index) const; 19 20 vectorInt& assign(const vectorInt &v); 21 int get_size() const; 22 23 private: 24 int size; 25 int *ptr; // ptr指向包含size个int的数组 26 }; 27 28 vectorInt::vectorInt(int n): size{n}, ptr{new int[size]} { 29 } 30 31 vectorInt::vectorInt(int n, int value): size{n}, ptr{new int[size]} { 32 for(auto i = 0; i < size; ++i) 33 ptr[i] = value; 34 } 35 36 vectorInt::vectorInt(const vectorInt &vi): size{vi.size}, ptr{new int[size]} { 37 for(auto i = 0; i < size; ++i) 38 ptr[i] = vi.ptr[i]; 39 } 40 41 vectorInt::~vectorInt() { 42 delete [] ptr; 43 } 44 45 const int& vectorInt::at(int index) const { 46 assert(index >= 0 && index < size); 47 48 return ptr[index]; 49 } 50 51 int& vectorInt::at(int index) { 52 assert(index >= 0 && index < size); 53 54 return ptr[index]; 55 } 56 57 vectorInt& vectorInt::assign(const vectorInt &v) { 58 delete[] ptr; // 释放对象中ptr原来指向的资源 59 60 size = v.size; 61 ptr = new int[size]; 62 63 for(int i = 0; i < size; ++i) 64 ptr[i] = v.ptr[i]; 65 66 return *this; 67 } 68 69 int vectorInt::get_size() const { 70 return size; 71 }
1 #include "vectorInt.hpp" 2 #include <iostream> 3 4 using std::cin; 5 using std::cout; 6 7 void output(const vectorInt &vi) { 8 for(auto i = 0; i < vi.get_size(); ++i) 9 cout << vi.at(i) << ", "; 10 cout << "\b\b \n"; 11 } 12 13 14 void test1() { 15 int n; 16 cout << "Enter n: "; 17 cin >> n; 18 19 vectorInt x1(n); 20 for(auto i = 0; i < n; ++i) 21 x1.at(i) = i*i; 22 cout << "x1: "; output(x1); 23 24 vectorInt x2(n, 42); 25 vectorInt x3(x2); 26 x2.at(0) = -999; 27 cout << "x2: "; output(x2); 28 cout << "x3: "; output(x3); 29 } 30 31 void test2() { 32 const vectorInt x(5, 42); 33 vectorInt y(10, 0); 34 35 cout << "y: "; output(y); 36 y.assign(x); 37 cout << "y: "; output(y); 38 39 cout << "x.at(0) = " << x.at(0) << endl; 40 cout << "y.at(0) = " << y.at(0) << endl; 41 } 42 43 int main() { 44 cout << "测试1: \n"; 45 test1(); 46 47 cout << "\n测试2: \n"; 48 test2(); 49 }
问题1：深复制，新对象分配了一个与原始对象 vi 相同大小的整数数组，并逐个复制 vi.ptr 数组中的元素到新对象的 ptr 数组中
问题2：如果将at()方法的返回值类型从int&和const int&更改为int，则这些方法将返回数组元素的副本，而不是元素的直接引用。调用者将无法通过at()方法修改数组中的值，因为返回的是值的副本。
问题3：如果将assign()方法的返回值类型从vectorInt&更改为vectorInt，返回当前对象的一个副本。这样复制整个数组，造成了不必要的开销。
运行结果截图：
task4.cpp
1 #pragma once 2 3 #include <iostream> 4 #include <cassert> 5 6 using std::cout; 7 using std::endl; 8 9 // 类Matrix的声明 10 class Matrix { 11 public: 12 Matrix(int n, int m); // 构造函数，构造一个n*m的矩阵, 初始值为value 13 Matrix(int n); // 构造函数，构造一个n*n的矩阵, 初始值为value 14 Matrix(const Matrix& x); // 复制构造函数， 使用已有的矩阵X构造 15 ~Matrix(); 16 17 void set(const double* pvalue); // 用pvalue指向的连续内存块数据按行为矩阵赋值 18 void clear(); // 把矩阵对象的值置0 19 20 const double& at(int i, int j) const; // 返回矩阵对象索引(i,j)的元素const引用 21 double& at(int i, int j); // 返回矩阵对象索引(i,j)的元素引用 22 23 int get_lines() const; // 返回矩阵对象行数 24 int get_cols() const; // 返回矩阵对象列数 25 26 void display() const; // 按行显示矩阵对象元素值 27 28 private: 29 int lines; // 矩阵对象内元素行数 30 int cols; // 矩阵对象内元素列数 31 double* ptr; 32 }; 33 34 Matrix::Matrix(int n, int m) : lines(n), cols(m), ptr(new double[n * m]()) { 35 // 初始化一个n*m的矩阵，所有元素为0 36 for (int i = 0; i < n * m; ++i) { 37 ptr[i] = 0; 38 } 39 } 40 41 Matrix::Matrix(int n) : Matrix(n, n) {} // 调用另一个构造函数实现n*n矩阵 42 43 Matrix::Matrix(const Matrix& x) : lines(x.lines), cols(x.cols), ptr(new double[x.lines * x.cols]) { 44 // 复制构造函数 45 for (int i = 0; i < lines * cols; ++i) { 46 ptr[i] = x.ptr[i]; 47 } 48 } 49 50 Matrix::~Matrix() { 51 delete[] ptr; // 释放内存 52 } 53 54 void Matrix::set(const double* pvalue) { 55 int k = 0; 56 for (int i = 0; i < lines; ++i) { 57 for (int j = 0; j < cols; ++j) { 58 ptr[i * cols + j] = pvalue[k++]; 59 } 60 } 61 } 62 63 void Matrix::clear() { 64 for (int i = 0; i < lines * cols; ++i) { 65 ptr[i] = 0; 66 } 67 } 68 69 const double& Matrix::at(int i, int j) const { 70 assert(i >= 0 && i < lines && j >= 0 && j < cols); 71 return ptr[i * cols + j]; 72 } 73 74 double& Matrix::at(int i, int j) { 75 assert(i >= 0 && i < lines && j >= 0 && j < cols); 76 return ptr[i * cols + j]; 77 } 78 79 int Matrix::get_lines() const { 80 return lines; 81 } 82 83 int Matrix::get_cols() const { 84 return cols; 85 } 86 87 void Matrix::display() const { 88 for (int i = 0; i < lines; ++i) { 89 for (int j = 0; j < cols; ++j) { 90 cout << ptr[i * cols + j] << " "; 91 } 92 cout << endl; 93 } 94 }
1 #include "matrix.hpp" 2 #include <iostream> 3 #include <cassert> 4 5 using std::cin; 6 using std::cout; 7 using std::endl; 8 9 10 const int N = 1000; 11 12 // 输出矩阵对象索引为index所在行的所有元素 13 void output(const Matrix& m, int index) { 14 assert(index >= 0 && index < m.get_lines()); 15 16 for (auto j = 0; j < m.get_cols(); ++j) 17 cout << m.at(index, j) << ", "; 18 cout << "\b\b \n"; 19 } 20 21 22 void test1() { 23 double x[1000] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 }; 24 25 int n, m; 26 cout << "Enter n and m: "; 27 cin >> n >> m; 28 29 Matrix m1(n, m); // 创建矩阵对象m1, 大小n×m 30 m1.set(x); // 用一维数组x的值按行为矩阵m1赋值 31 32 Matrix m2(m, n); // 创建矩阵对象m1, 大小m×n 33 m2.set(x); // 用一维数组x的值按行为矩阵m1赋值 34 35 Matrix m3(2); // 创建一个2×2矩阵对象 36 m3.set(x); // 用一维数组x的值按行为矩阵m4赋值 37 38 cout << "矩阵对象m1: \n"; m1.display(); cout << endl; 39 cout << "矩阵对象m2: \n"; m2.display(); cout << endl; 40 cout << "矩阵对象m3: \n"; m3.display(); cout << endl; 41 } 42 43 void test2() { 44 Matrix m1(2, 3); 45 m1.clear(); 46 47 const Matrix m2(m1); 48 m1.at(0, 0) = -999; 49 50 cout << "m1.at(0, 0) = " << m1.at(0, 0) << endl; 51 cout << "m2.at(0, 0) = " << m2.at(0, 0) << endl; 52 cout << "矩阵对象m1第0行: "; output(m1, 0); 53 cout << "矩阵对象m2第0行: "; output(m2, 0); 54 } 55 56 int main() { 57 cout << "测试1: \n"; 58 test1(); 59 60 cout << "测试2: \n"; 61 test2(); 62 }
运行结果截图：
task5.cpp
1 #ifndef USER_HPP 2 #define USER_HPP 3 4 #include <string> 5 #include <iostream> 6 7 class User { 8 private: 9 std::string name; 10 std::string password; 11 std::string email; 12 13 public: 14 // 构造函数 15 User(const std::string& uname) 16 : name(uname), password("123456"), email("") {} 17 18 User(const std::string& uname, const std::string& pwd, const std::string& eml) 19 : name(uname), password(pwd), email(eml) {} 20 21 // 设置邮箱 22 void set_email() { 23 std::string input; 24 bool valid = false; 25 int attempts = 0; 26 27 while (!valid && attempts < 3) { 28 std::cout << "Enter email address: "; 29 std::cin >> input; 30 31 if (input.find('@') != std::string::npos) { 32 valid = true; 33 email = input; 34 } 35 else { 36 std::cout << "illegal email.Please re-enter email:" << std::endl; 37 attempts++; 38 } 39 } 40 41 if (attempts == 3) { 42 std::cout << "password input error.Please try after a while." << std::endl; 43 } 44 } 45 46 // 修改密码 47 void change_password() { 48 std::string old_pwd, new_pwd; 49 bool valid = false; 50 int attempts = 0; 51 52 while (!valid && attempts < 3) { 53 std::cout << "Enter old password: "; 54 std::cin >> old_pwd; 55 56 if (old_pwd == password) { 57 valid = true; 58 break; 59 } 60 else { 61 std::cout << "password input error.Please re-enter again:" << std::endl; 62 attempts++; 63 } 64 } 65 66 if (valid) { 67 std::cout << "Enter new password: "; 68 std::cin >> new_pwd; 69 password = new_pwd; 70 } 71 else { 72 std::cout << "password input error.Please try after a while." << std::endl; 73 } 74 } 75 76 // 显示用户信息 77 void display() const { 78 std::cout << "name: " << name << std::endl; 79 std::cout << "pass: "; 80 for (char ch : password) { 81 std::cout << '*'; 82 } 83 std::cout << std::endl; 84 std::cout << "email: " << email << std::endl; 85 } 86 }; 87 88 #endif // USER_HPP
1 #include "user.hpp" 2 #include <iostream> 3 #include <vector> 4 #include <string> 5 6 using std::cin; 7 using std::cout; 8 using std::endl; 9 using std::vector; 10 using std::string; 11 12 void test() { 13 vector<User> user_lst; 14 15 User u1("Alice", "2024113", "Alice@hotmail.com"); 16 user_lst.push_back(u1); 17 cout << endl; 18 19 User u2("Bob"); 20 u2.set_email(); 21 u2.change_password(); 22 user_lst.push_back(u2); 23 cout << endl; 24 25 User u3("Hellen"); 26 u3.set_email(); 27 u3.change_password(); 28 user_lst.push_back(u3); 29 cout << endl; 30 31 cout << "There are " << user_lst.size() << " users. they are: " << endl; 32 for(auto &i: user_lst) { 33 i.display(); 34 cout << endl; 35 } 36 } 37 38 int main() { 39 test(); 40 }
运行结果截图：
task6.cpp:
1 #ifndef __DATE_H__ 2 #define __DATE_H__ 3 class Date { 4 private: 5 int year; 6 int month; 7 int day; 8 int totalDays; 9 public: 10 Date(int year, int month, int day); 11 int getYear()const { return year; } 12 int getMonth()const { return month; } 13 int getDay()const { return day; } 14 int getMaxDay()const; 15 bool isLeapYear()const { 16 return year % 4 == 0 && year % 100 != 0 || year % 400 == 0; 17 } 18 void show()const; 19 int distance(const Date& date)const { 20 return totalDays - date.totalDays; 21 } 22 }; 23 #endif//__DATE_H__
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 }
1 #ifndef __ACCOUNT_H__ 2 #define __aCCOUNT_H__ 3 #include"date.h" 4 #include<string> 5 class SavingsAccount { 6 private: 7 std::string id; 8 double balance; 9 double rate; 10 Date lastDate; 11 double accumulation; 12 static double total; 13 void record(const Date& date, double amount, const std::string& desc); 14 void error(const std::string& msg)const; 15 double accumulate(const Date& date)const { 16 return accumulation + balance * date.distance(lastDate); 17 } 18 public: 19 SavingsAccount(const Date& date, const std::string& id, double rate); 20 const std::string& getID()const { return id; } 21 double getBalance()const { return balance; } 22 double getRate()const { return rate; } 23 static double getTotal() { 24 return total; 25 } 26 void deposit(const Date& date, double amount, const std::string& desc); 27 void withdraw(const Date& date, double amount, const std::string& desc); 28 void settle(const Date& date); 29 void show()const; 30 }; 31 #endif //__ACCOUNT_H__
1 #include "account.h" 2 #include<cmath> 3 #include<iostream> 4 using namespace std; 5 double SavingsAccount::total = 0; 6 SavingsaAccount::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 / date.distance(Date(date.getYear() - 1, 1, 1)); 33 if (interest != 0) 34 record(date, interest, "interest"); 35 accumulation = 0; 36 } 37 void SavingsAccount::show()const { 38 cout << id << "\tBalance:" << balance; 39 }
1 #include"account.h" 2 #include<iostream> 3 using namespace std; 4 int main() { 5 Date date(2008, 11, 1); 6 SavingsAccount accounts[] = { SavinsAccount(date,"03755217",0.015),SavingsAccount(date,"02342342",0.015) }; 7 const int n = sizeof(accounts) / sizeof(SavingsAccount); 8 accounts[0].deposit(Date(2008, 11, 5), 5000, "salary"); 9 accounts[0].deposit(Date(2008, 11, 25), 10000, "sell stock 0323"); 10 accounts[0].deposit(Date(2008, 12, 5), 5500, "salary"); 11 accounts[0].withdraw(Date(2008, 12, 20), 4000, "buy a laptop"); 12 cout << endl; 13 for (int i = 0; i < n; i++) { 14 accounts[i].settle(Date(2009, 1, 1)); 15 accounts[i].show(); 16 cout << endl; 17 } 18 cout << "Total:" << SavinsAccount::getTotal() << endl; 19 return 0; 20 }
运行结果截图：
