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 // 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 }
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 }
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 }
问题1：定义了2个类 Button和window.使用了标准的两个类 string和vector。
问题2: 剩下的函数主要是一些负责输出结果的函数，它们在输出的过程中不会改变对象的值，所以我觉得没有必要加const，当然它们属于简单的输出语句可以设计成内联函数.
问题3：定义一个长度为40且元素都是'*'的string对象s.
任务2：
task2:
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 }
问题1：第一行定义一个长度为5值全为42的整形vector对象v1,第二行使用v1复制构造了一个vector对象v2,第三行对v1的第一个值进行修改.
问题2：第一行定义一个vetcor<int> 类型的vector对象v1,第二行使用复制构造函数定义了一个vector<int> 类型的vetcor对象v2.
问题3：分别使用问题二定义的v1,v2的第一个元素，复制定义两个整形的vector数组，并输出它们的最后一个元素.
问题4:实现的机制是深复制，是.
任务3：
vectorInt.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 }
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 }
问题1:深复制。
问题2：不能正常运行.是，const int& at(int index) const;返回的是引用类型，也就是可以通过它返回值对新的引用变量进行赋值，新的变量在后续操作的过程可能会改变它的值，如果是const对象，它是不允许值发生改变，所以因该加上const.
问题3：可以改成，这段代码的本质就是利用一个const vectorInt进行重新赋值，使不使用引用，对这个过程没有影响，只不过在调用这个函数的时候会有额外内存开销.
任务4：
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：待补足 35 // xxx 36 Matrix::Matrix(int n, int m): lines(n), cols(m) { 37 ptr = new double[n*m]; 38 clear(); 39 } 40 Matrix::Matrix(int n): Matrix(n, n) {} 41 Matrix::Matrix(const Matrix &x): lines(x.lines), cols(x.cols) { 42 ptr = new double[lines*cols]; 43 for(int i=0;i<lines*cols;i++) 44 ptr[i] = x.ptr[i]; 45 } 46 Matrix::~Matrix() { 47 delete[] ptr; 48 } 49 void Matrix::set(const double *pvalue) { 50 for(int i=0;i<lines*cols;i++) 51 ptr[i] = pvalue[i]; 52 } 53 54 void Matrix::clear() { 55 for(int i=0;i<lines*cols;i++) 56 ptr[i] = 0; 57 } 58 const double& Matrix::at(int i, int j) const{ 59 assert(i>=0 && i<lines && j>=0 && j<cols); 60 return ptr[i*cols+j]; 61 } 62 double &Matrix::at(int i, int j) { 63 assert(i >= 0 && i < lines && j >= 0 && j < cols); 64 return ptr[i * cols + j]; 65 } 66 67 int Matrix::get_lines() const { 68 return lines; 69 } 70 int Matrix::get_cols() const { 71 return cols; 72 } 73 74 void Matrix::display() const { 75 for(int i=0;i<lines;i++) { 76 for(int j=0;j<cols;j++) { 77 cout << ptr[i*cols+j] << " "; 78 } 79 cout << endl; 80 } 81 }
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 }
任务5：
user.hpp:
1 #include <iostream> 2 #include <string> 3 4 using namespace std; 5 6 class User { 7 public: 8 User(string name, string email="", string password="123456"):name(name), email(email), password(password) {} 9 void set_email(); 10 void change_password(); 11 void display(); 12 13 private: 14 string name; 15 string email; 16 string password; 17 18 19 }; 20 void User::set_email() 21 { 22 string new_email; 23 while(1){ 24 cout << "Enter new email: "; 25 cin>>new_email; 26 if(new_email.find("@") == string::npos || new_email.find(".") == string::npos){ 27 cout << "Invalid email format. Please try again.\n"; 28 } 29 else{ 30 email = new_email; 31 cout<<"Email is set successfully.\n"; 32 break; 33 } 34 } 35 36 } 37 38 void User::change_password() 39 { 40 string new_password; 41 string old_password; 42 for(int i=0; i<3; i++) 43 { 44 cout<<"Enter old password: "; 45 cin>>old_password; 46 if(password == old_password) 47 { 48 cout<<"Enter new password: "; 49 cin>>new_password; 50 password = new_password; 51 cout<<"Password changed successfully.\n"; 52 return; 53 } 54 else 55 { 56 cout<<"Incorrect password. Please try again.\n"; 57 } 58 } 59 cout<<"Too many incorrect attempts. Account locked.\n"; 60 } 61 62 void User::display() 63 { 64 cout<<"Name: "<<name<<"\n"; 65 cout<<"Password: "<<string(password.size(), '*')<<"\n"; 66 cout<<"Email: "<<email<<"\n"; 67 68 }
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 }
任务6：
date.h:
1 #pragma once 2 class Date { 3 private: 4 int year; 5 int month; 6 int day; 7 int totalDays; 8 public: 9 Date(int year, int month, int day); 10 int getYear()const { 11 return year; 12 } 13 int getMonth()const { 14 return month; 15 } 16 int getDay()const { 17 return day; 18 } 19 int getMaxDay()const; 20 bool isLeapYear()const { 21 return year % 4 == 0 && year % 100 != 0 || year % 400 == 0; 22 } 23 void show()const; 24 int distance(const Date& date)const { 25 return totalDays - date.totalDays; 26 } 27 };
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 }
account.h:
1 #include"date.h" 2 #include<string> 3 class SavingsAccount { 4 private: 5 std::string id; 6 double balance; 7 double rate; 8 Date lastDate; 9 double accumulation; 10 static double total; 11 void record(const Date& date, double amount, const std::string& desc); 12 void error(const std::string& msg)const; 13 double accumulate(const Date& date)const { 14 return accumulation + balance * date.distance(lastDate); 15 } 16 public: 17 SavingsAccount(const Date& date, const std::string& id, double rate); 18 const std::string& getId()const { 19 return id; 20 } 21 double getBalance()const { 22 return balance; 23 } 24 double getRate()const { 25 return rate; 26 } 27 static double getTotal() { 28 return total; 29 } 30 void deposit(const Date& date, double amount, const std::string& desc); 31 void withdraw(const Date& date, double amount, const std::string& desc); 32 void settle(const Date& date); 33 void show()const; 34 };
account.cpp:
1 #include"account.h" 2 #include<cmath> 3 #include<iostream> 4 using namespace std; 5 double SavingsAccount::total = 0; 6 7 SavingsAccount::SavingsAccount(const Date& date, const string& id, double rate) :id(id), balance(0), rate(rate), lastDate(date), accumulation(0) { 8 date.show(); 9 cout << "\t#" << id << "created" << endl; 10 } 11 void SavingsAccount::record(const Date& date, double amount, const std::string& desc) { 12 accumulation = accumulate(date); 13 lastDate = date; 14 amount = floor(amount * 100 + 0.5) / 100; 15 balance += amount; 16 total += amount; 17 date.show(); 18 cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl; 19 } 20 void SavingsAccount::error(const std::string& msg)const { 21 cout << "Error(#" << id << ");" << msg << endl; 22 } 23 void SavingsAccount::deposit(const Date& date, double amount, const std::string& desc) { 24 record(date, amount, desc); 25 } 26 void SavingsAccount::withdraw(const Date& date, double amount, const std::string& desc) { 27 if (amount > getBalance()) { 28 error("not enough money"); 29 } else 30 record(date, -amount, desc); 31 } 32 void SavingsAccount::settle(const Date& date) { 33 double interest = accumulate(date) * rate / 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 }
task6.cpp:
1 #include"account.h" 2 #include<iostream> 3 using namespace std; 4 int main() { 5 Date date(2008, 11, 1); 6 SavingsAccount accounts[] = { 7 SavingsAccount(date,"03755217",0.015), 8 SavingsAccount(date,"02342342",0.015) 9 }; 10 const int n = sizeof(accounts) / sizeof(SavingsAccount); 11 accounts[0].deposit(Date(2008, 11, 5), 5000, "salary"); 12 accounts[1].deposit(Date(2008, 11, 25), 10000, "sell stock 0323"); 13 14 accounts[0].deposit(Date(2008, 12, 5), 5000, "salary"); 15 accounts[1].withdraw(Date(2008, 12, 20), 4000, "buy a laptop"); 16 17 cout << endl; 18 for (int i = 0; i < n; i++) { 19 accounts[i].settle(Date(2009, 1, 1)); 20 accounts[i].show(); 21 cout << endl; 22 } 23 cout << "Total:" << SavingsAccount::getTotal() << endl; 24 return 0; 25 }
