实验任务1：
代码：
button.hpp
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 }
window.hpp
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 }
task1.cpp
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 }
运行结果截图：
回答问题：
问题1：自定义了两个类，使用到了标准库的vector类，自定义的Button类和vector之间存在组合关系、vector
和自定义的Window类之间存在组合关系
问题2：有一些，如add_button，涉及到数据改变的，不能设置为const成员函数。在已经添加了inline的函数之外，其余函数的操作都很简单，没有必要设置为inline。
问题3：字符串s = 40个*
实验任务2：
代码：
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 24 v1.at(0) = -999; 25 cout << "v1: "; output1(v1); 26 cout << "v2: "; output1(v2); 27 cout << "v1.at(0) = " << v1.at(0) << endl; 28 cout << "v2.at(0) = " << v2.at(0) << endl; 29 } 30 31 void test2() { 32 vector<vector<int>> v1{{1, 2, 3}, {4, 5, 6, 7}}; 33 const vector<vector<int>> v2(v1); 34 35 v1.at(0).push_back(-999); 36 cout << "v1: \n"; output2(v1); 37 cout << "v2: \n"; output2(v2); 38 39 vector<int> t1 = v1.at(0); 40 cout << t1.at(t1.size()-1) << endl; 41 42 const vector<int> t2 = v2.at(0); 43 cout << t2.at(t2.size()-1) << endl; 44 } 45 46 int main() { 47 cout << "测试1:\n"; 48 test1(); 49 50 cout << "\n测试2:\n"; 51 test2(); 52 }
运行结果截图：
回答问题：
问题1：21行构造了一个名字为v1的vctor<int>动态数组，并且v1在构造时同时初始化，存放了5个42。22行借助v1复制构造了v2。24行调用at()，把v1的第0项赋值为-999。
问题2：32行构造了一个名字为v1的二维vctor动态数组，并且v1在构造时同时初始化。22行借助v1复制构造了v2，v2是const常量。35行调用at()和push_back()，在v1的第0行的末尾追加了一个数-999。
问题3：39行构造了一个vector<int>动态数组t1，并用二维数组v1的第零行初始化。40行输出t1最后一个数据。42行构造了一个const vector<int>的对象t2，并用v2的第零行初始化。第43行输出t2的最后一个数据。
问题4：标准库模板类vector内部封装的复制构造函数，其实现机制是深复制。模板类vector的接口at(), 不需要至少提供一个const成员函数作为接口。
实验任务3：
代码：
vectorInt.hpp
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 }
task3.cpp
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 }
运行结果截图：
回答问题：
问题1：深复制
问题2：vectorInt类中，两个at()接口，如果返回值类型改成int而非int&（相应地，实现部分也同步修改），测试代码不能正确运行。因为测试代码中x2.at(0) = -999这样的调用，表明需要修改x2内部的值，所以返回值必须是int&。如果把line18返回值类型前面的const去掉，针对这个测试代码，有潜在安全隐患。因为在test2中存在const vectorInt x(5, 42)，所以去掉后会报错。
问题3：在目前的测试代码中，这样修改没有问题。
实验任务4：
代码：
matrix.hpp
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 // 类Matrix的实现： 35 Matrix::Matrix(int n, int m) : lines{ n }, cols{ m } { 36 ptr = new double[n * m]; 37 } 38 39 Matrix::Matrix(int n) : lines{ n }, cols{ n } { 40 ptr = new double[n * n]; 41 } 42 43 Matrix::Matrix(const Matrix& x) : lines{ x.lines }, cols{x.cols} { 44 ptr = new double[x.lines * x.cols]; 45 for (auto i = 0; i < x.lines * x.cols; i++) 46 *(ptr + i) = *(x.ptr + i); 47 } 48 49 Matrix::~Matrix() {} 50 51 void Matrix::set(const double* pvalue) { 52 for (auto i = 0; i < lines * cols; i++) 53 *(ptr + i) = *(pvalue + i); 54 } 55 56 void Matrix::clear() { 57 for (auto i = 0; i < lines * cols; i++) 58 *(ptr + i) = 0; 59 } 60 61 const double& Matrix::at(int i, int j) const { 62 return *(ptr + lines * i + j); 63 } 64 65 double& Matrix::at(int i, int j) { 66 return *(ptr + lines * i + j); 67 } 68 69 int Matrix::get_lines() const { 70 return lines; 71 } 72 73 int Matrix::get_cols() const { 74 return cols; 75 } 76 77 void Matrix::display() const { 78 for (auto i = 0; i < lines; i++) { 79 for (auto j = 0; j < cols; j++) { 80 cout << *(ptr + i * cols + j) << ", "; 81 cout << "\b\b "; 82 } 83 cout << endl; 84 } 85 }
task4.cpp
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 }
测试结果截图：
实验任务5：
代码：
user.hpp
1 #pragma once 2 #include <iostream> 3 #include <iomanip> 4 5 using namespace std; 6 7 class User { 8 public: 9 User(string n, string p = "123456", string e = "\0"); 10 11 void set_email(); 12 void change_password(); 13 void display() const; 14 15 bool check_email(string e); 16 17 private: 18 string name; 19 string password; 20 string email; 21 }; 22 23 User::User(string n, string p, string e) : name{ n }, password{ p }, email{ e } { 24 25 } 26 27 bool User::check_email(string e) { 28 auto pos = e.find("@"); 29 if (pos == e.npos) { 30 cout << "illegal email. Please re-enter email: "; 31 return false; 32 } 33 else { 34 cout << "email is set successfully..." << endl; 35 return true; 36 } 37 } 38 39 void User::set_email() { 40 cout << "Enter email address: "; 41 string e; 42 cin >> e; 43 44 if (check_email(e)) 45 email = e; 46 else 47 set_email(); 48 } 49 50 void User::change_password() { 51 cout << "Enter old password: "; 52 string p; 53 cin >> p; 54 55 int i = 1; 56 for (; i <= 3; i++) { 57 if (p == password) { 58 cout << "Enter new password: "; 59 cin >> password; 60 cout << "new password is set successfully..." << endl; 61 break; 62 } 63 else if (p != password && i == 3) 64 cout << "password input error. Please try after a while." << endl; 65 else { 66 cout << "password input error. Please re-enter again: "; 67 cin >> p; 68 } 69 } 70 } 71 72 void User::display() const { 73 cout << setiosflags(ios::left) << setw(10) << "name:" << name << endl; 74 string p(password.size(), '*'); 75 cout << setiosflags(ios::left) << setw(10) << "pass:" << p << endl; 76 cout << setiosflags(ios::left) << setw(10) << "email:" << email << endl; 77 }
task5.cpp
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：
实验任务6：
date.h
1 #pragma once 2 3 class Date { 4 private: 5 int year; 6 int month; 7 int day; 8 int totalDays; 9 10 public: 11 Date(int year, int month, int day); 12 int getYear() const { return year; } 13 int getMonth() const { return month; } 14 int getDay() const { return day; } 15 int getMaxDay() const; 16 bool isLeapYear() const { 17 return year % 4 == 0 && year % 100 != 0 || year % 400 == 0; 18 } 19 void show() const; 20 int distance(const Date& date) const { 21 return totalDays - date.totalDays; 22 } 23 };
date.cpp
1 #include "date.h" 2 #include <iostream> 3 #include <cstdlib> 4 5 using namespace std; 6 7 namespace { 8 const int DAYS_BEFORE_MONTH[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }; 9 } 10 11 int Date::getMaxDay() const { 12 if (isLeapYear() && month == 2) 13 return 29; 14 else 15 return DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1]; 16 } 17 18 void Date::show() const{ 19 cout << getYear() << "-" << getMonth() << "-" << getDay(); 20 } 21 22 Date::Date(int year, int month, int day) : year{ year }, month{ month }, day{ day } { 23 if (day <= 0 || day > getMaxDay()) { 24 cout << "Invalid date: "; 25 show(); 26 cout << endl; 27 exit(1); 28 } 29 int years = year - 1; 30 totalDays = years * 365 + years / 4 - years / 100 + years / 400 31 + DAYS_BEFORE_MONTH[month - 1] + day; 32 if (isLeapYear() && month > 2) totalDays++; 33 }
account.h
1 #pragma once 2 #include "date.h" 3 #include <string> 4 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 14 void record(const Date& date, double amount, const std::string& desc); 15 void error(const std::string& msg) const; 16 double accumulate(const Date& date) const { 17 return accumulation + balance * date.distance(lastDate); 18 } 19 20 public: 21 SavingsAccount(const Date& date, const std::string& id, double rate); 22 const std::string& getId() const { return id; } 23 double getBalance() const { return balance; } 24 double getRate() const { return rate; } 25 static double getTotal() { return total; } 26 27 void deposit(const Date& date, double amount, const std::string& desc); 28 void withdraw(const Date& date, double amount, const std::string& desc); 29 void settle(const Date& date); 30 void show() const; 31 };
account.cpp
1 #include "account.h" 2 #include <cmath> 3 #include <iostream> 4 5 using namespace std; 6 7 double SavingsAccount::total = 0; 8 9 SavingsAccount::SavingsAccount(const Date& date, const string& id, double rate) : 10 id{ id }, balance{ 0 }, rate{ rate }, lastDate{ date }, accumulation{ 0 } { 11 date.show(); 12 cout << "\t#" << id << "created" << endl; 13 } 14 15 void SavingsAccount::record(const Date& date, double amount, const string& desc) { 16 accumulation = accumulate(date); 17 lastDate = date; 18 amount = floor(amount * 100 + 0.5) / 100; 19 balance += amount; 20 total += amount; 21 date.show(); 22 cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl; 23 } 24 25 void SavingsAccount::error(const string& msg) const { 26 cout << "Error(#" << id << "):" << msg << endl; 27 } 28 29 void SavingsAccount::deposit(const Date& date, double amount, const string& desc) { 30 record(date, amount, desc); 31 } 32 33 void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) { 34 if (amount > getBalance()) 35 error("not enough money"); 36 else 37 record(date, -amount, desc); 38 } 39 40 void SavingsAccount::settle(const Date& date) { 41 double interest = accumulate(date) * rate 42 / date.distance(Date(date.getYear() - 1, 1, 1)); 43 if (interest != 0) 44 record(date, interest, "interest"); 45 accumulation = 0; 46 } 47 48 void SavingsAccount::show() const { 49 cout << id << "\tBalance:" << balance; 50 }
6_25.cpp
1 #include "account.h" 2 #include <iostream> 3 4 using namespace std; 5 6 int main() { 7 Date date(2008, 11, 1); 8 SavingsAccount accounts[] = { 9 SavingsAccount(date, "03755217", 0.015), 10 SavingsAccount(date, "02342342", 0.015) 11 }; 12 const int n = sizeof(accounts) / sizeof(SavingsAccount); 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 22 for (int i = 0; i < n; i++) { 23 accounts[i].settle(Date(2009, 1, 1)); 24 accounts[i].show(); 25 cout << endl; 26 } 27 28 cout << "Total:" << SavingsAccount::getTotal() << endl; 29 }
运行结果截图:
