实验3 类和对象
实验任务1：
代码：
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 #define _CRT_SECURE_NO_WARNINGS 1 2 3 #include "window.hpp" 4 #include<iostream> 5 6 using std::cout; 7 using std::cin; 8 9 void test() { 10 window w1("new window"); 11 w1.add_button("maximize"); 12 w1.display(); 13 w1.close(); 14 } 15 16 int main() { 17 cout << "用组合类模拟简单GUI：\n"; 18 test(); 19 }
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问题1：
两个类（button和window）vector,string.button和string，window和button以及string以及vector.
问题2：
不合适。因为加了const之后不可修改，加了inline是为了提高效率，对于较复杂的程序随意加上这两个关键字可能会出错。
问题3：
创建1个string s，内容是40个*，分开各部分代码。
实验任务2：
代码：
1 #define _CRT_SECURE_NO_WARNINGS 1 2 3 #include<iostream> 4 #include<vector> 5 6 using namespace std; 7 8 void output1(const vector<int>& v) { 9 for (auto& i : v) { 10 cout << i << ", "; 11 } 12 cout << "\b\b \n"; 13 } 14 15 void output2(const vector<vector<int>> v) { 16 for (auto& i : v) { 17 for (auto& j : i) { 18 cout << j << ", "; 19 } 20 cout << "\b\b \n"; 21 } 22 } 23 24 void test1() { 25 vector<int> v1(5, 42); 26 const vector<int> v2(v1); 27 28 v1.at(0) = -999; 29 cout << "v1: "; output1(v1); 30 cout << "v2: "; output1(v2); 31 cout << "v1.at(0) = " << v1.at(0) << endl; 32 cout << "v2.at(0) = " << v2.at(0) << endl; 33 } 34 35 void test2() { 36 vector<vector<int>>v1{ {1,2,3},{4,5,6,7} }; 37 const vector<vector<int>> v2(v1); 38 39 v1.at(0).push_back(-999); 40 cout << "v1: \n"; output2(v1); 41 cout << "v2: \n"; output2(v2); 42 43 vector<int>t1 = v1.at(0); 44 cout << t1.at(t1.size() - 1) << endl; 45 46 const vector<int>t2 = v2.at(0); 47 cout << t2.at(t2.size() - 1) << endl; 48 } 49 50 int main() { 51 cout << "测试1:\n"; 52 test1(); 53 54 cout << "\n测试2;\n"; 55 test2(); 56 }
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问题1：
21：创建一个元素为整型的可变长数组v1，元素是5个42；
22：创建一个元素为整型的可变长数组v2，元素与v1相同，是5个42；
24：将v1的第一个数改为-999.
问题2：
创建一个元素为元素是可变长数组容器的可变长数组容器v1，元素是{1，2，3}和{4，5，6，7}；
创建一个元素为元素是可变长数组容器的可变长数组容器v2，深复制v1，元素是{1，2，3}和{4，5，6，7}；
将v1第一个元素中的第一个元素改为-999；
问题3：
39，42：得到当前数组的第一个元素；
40，43：输出当前数组的最后一个元素。
问题4：
深复制；需要。
实验任务3：
代码：
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 37 vectorInt::vectorInt(const vectorInt& vi) :size{ vi.size }, ptr{ new int[size] } { 38 for (auto i = 0; i < size; i++) { 39 ptr[i] = vi.ptr[i]; 40 } 41 } 42 43 vectorInt::~vectorInt() { 44 delete[] ptr; 45 } 46 47 const int& vectorInt::at(int index)const { 48 assert(index >= 0 && index < size); 49 50 return ptr[index]; 51 } 52 53 int& vectorInt::at(int index){ 54 assert(index >= 0 && index < size); 55 56 return ptr[index]; 57 } 58 59 vectorInt& vectorInt::assign(const vectorInt& v) { 60 delete[] ptr; //释放对象中ptr原本指向的资源 61 62 size = v.size; 63 ptr = new int[size]; 64 65 for (int i = 0; i < size; i++) { 66 ptr[i] = v.ptr[i]; 67 } 68 69 return *this; 70 } 71 72 int vectorInt::get_size()const { 73 return size; 74 }
1 #define _CRT_SECURE_NO_WARNINGS 1 2 3 #include"vectorInt.hpp" 4 #include<iostream> 5 6 using std::cin; 7 using std::cout; 8 9 void output(const vectorInt& vi) { 10 for (auto i = 0; i < vi.get_size(); i++) { 11 cout << vi.at(i) << ", "; 12 } 13 cout << "\b\b\n"; 14 } 15 16 17 void test1() { 18 int n; 19 cout << "Enter n: "; 20 cin >> n; 21 22 vectorInt x1(n); 23 for (auto i = 0; i < n; i++) { 24 x1.at(i) = i * i; 25 } 26 cout << "x1: "; output(x1); 27 28 vectorInt x2(n, 42); 29 vectorInt x3(x2); 30 x2.at(0) = -999; 31 cout << "x2: ";output(x2); 32 cout << "x3: "; output(x3); 33 } 34 35 void test2() { 36 const vectorInt x(5, 42); 37 vectorInt y(10, 0); 38 39 cout << "y: "; output(y); 40 y.assign(x); 41 cout << "y: "; output(y); 42 43 cout << "x.at(0) = " << x.at(0) << endl; 44 cout << "y.at(0) = " << y.at(0) << endl; 45 } 46 47 int main() { 48 cout << "测试1：\n"; 49 test1(); 50 51 cout << "\n测试2：\n"; 52 test2(); 53 }
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问题1：
深复制。
问题2：
不能。会有。
返回int，不能被赋值。
const去掉后，值可能被修改。
问题3：
可以。返回引用用引用接收，返回vectorInt用对象接收，是可以的。
实验任务4：
代码：
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); 13 Matrix(int n); 14 Matrix(const Matrix& x); 15 ~Matrix(); 16 17 void set(const double *pvalue); 18 void clear(); 19 20 const double& at(int i,int j)const; 21 double& at(int i, int j); 22 23 int get_lines()const; 24 int get_cols()const; 25 26 void display()const; 27 private: 28 int lines; 29 int cols; 30 double* ptr; 31 }; 32 33 Matrix::Matrix(int n, int m) :lines{ n }, cols{ m }, ptr{ new double[lines * cols] } { 34 for (int i = 0; i < n * m; i++) { 35 ptr[i] = 1;//设value为1 36 } 37 } 38 39 Matrix::Matrix(int n) :lines{ n }, cols{ n }, ptr{ new double[n * n] } { 40 for (int i = 0; i < n * n; i++) { 41 ptr[i] = 1; 42 } 43 } 44 45 Matrix::Matrix(const Matrix &x):lines{ x.lines }, cols{ x.cols }, ptr{ new double[lines*cols] } { 46 for (int i = 0; i < lines*cols; i++) { 47 ptr[i] = x.ptr[i]; 48 } 49 } 50 51 Matrix::~Matrix() { 52 delete[] ptr; 53 } 54 55 void Matrix::set(const double *pvalue) { 56 for (int i = 0; i < lines * cols; i++) { 57 ptr[i] = pvalue[i]; 58 } 59 } 60 61 void Matrix::clear() { 62 for (int i = 0; i < lines * cols; i++) { 63 ptr[i] = 0; 64 } 65 } 66 67 const double& Matrix::at(int i, int j)const { 68 return ptr[i*cols+j]; 69 } 70 double& Matrix::at(int i, int j) { 71 return ptr[i * cols + j]; 72 } 73 74 int Matrix::get_lines()const { 75 return lines; 76 } 77 int Matrix::get_cols()const { 78 return cols; 79 } 80 81 void Matrix::display()const { 82 for (int i = 0; i < lines; i++) { 83 for (int j = 0; j < cols; j++) { 84 cout << ptr[i * cols + j]<<", "; 85 } 86 cout << endl; 87 } 88 }
1 #define _CRT_SECURE_NO_WARNINGS 1 2 3 #include "matrix.hpp" 4 #include <iostream> 5 #include <cassert> 6 7 using std::cin; 8 using std::cout; 9 using std::endl; 10 11 12 const int N = 1000; 13 14 // 输出矩阵对象索引为index所在行的所有元素 15 void output(const Matrix& m, int index) { 16 assert(index >= 0 && index < m.get_lines()); 17 18 for (auto j = 0; j < m.get_cols(); ++j) 19 cout << m.at(index, j) << ", "; 20 cout << "\b\b \n"; 21 } 22 23 24 void test1() { 25 double x[1000] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 }; 26 27 int n, m; 28 cout << "Enter n and m: "; 29 cin >> n >> m; 30 31 Matrix m1(n, m); // 创建矩阵对象m1, 大小n×m 32 m1.set(x); // 用一维数组x的值按行为矩阵m1赋值 33 34 Matrix m2(m, n); // 创建矩阵对象m1, 大小m×n 35 m2.set(x); // 用一维数组x的值按行为矩阵m1赋值 36 37 Matrix m3(2); // 创建一个2×2矩阵对象 38 m3.set(x); // 用一维数组x的值按行为矩阵m4赋值 39 40 cout << "矩阵对象m1: \n"; m1.display(); cout << endl; 41 cout << "矩阵对象m2: \n"; m2.display(); cout << endl; 42 cout << "矩阵对象m3: \n"; m3.display(); cout << endl; 43 } 44 45 void test2() { 46 Matrix m1(2, 3); 47 m1.clear(); 48 49 const Matrix m2(m1); 50 m1.at(0, 0) = -999; 51 52 cout << "m1.at(0, 0) = " << m1.at(0, 0) << endl; 53 cout << "m2.at(0, 0) = " << m2.at(0, 0) << endl; 54 cout << "矩阵对象m1第0行: "; output(m1, 0); 55 cout << "矩阵对象m2第0行: "; output(m2, 0); 56 } 57 58 int main() { 59 cout << "测试1: \n"; 60 test1(); 61 62 cout << "测试2: \n"; 63 test2(); 64 }
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实验任务5：
代码：
1 #pragma once 2 3 #include<string> 4 #include<iostream> 5 6 using namespace std; 7 8 class User{ 9 public: 10 User(const string name1) :name{ name1 } { 11 password = "123456"; 12 } 13 User(const string name1, const string password1, const string email1) :name{ name1 }, password{ password1 }, email{ email1 } { 14 } 15 void set_email(); 16 void change_password(); 17 void display(); 18 bool isTrueEmail(string newEmail); 19 private: 20 string name; 21 string password; 22 string email; 23 }; 24 25 void User::set_email() { 26 cout << "Enter email address："; 27 string newEmail; 28 cin >> newEmail; 29 while(!isTrueEmail(newEmail)) { 30 cout << "illegal email. Please re-enter email: "; 31 cin >> newEmail; 32 } 33 cout << "email is set successfully..." << endl; 34 email = newEmail; 35 } 36 37 bool User::isTrueEmail(string newEmail) { 38 for (int i = 0; i < newEmail.size(); i++) { 39 if (newEmail[i]=='@') { 40 return true; 41 } 42 } 43 return false; 44 } 45 46 void User::change_password() { 47 cout << "Enter old password: "; 48 string newPassword; 49 cin >> newPassword; 50 int count = 0;//count记录输入密码错误的次数 51 while (newPassword != password) { 52 count++; 53 cout << "password input error. "; 54 if (count == 3) { 55 cout << "Please try after a while." << endl; 56 return; 57 } 58 cout<<"Please re-enter again : "; 59 cin >> newPassword; 60 } 61 cout << "Enter new password: "; 62 cin >> newPassword; 63 password = newPassword; 64 cout << "new password is set successfully..." << endl; 65 } 66 67 void User::display() { 68 cout << "name: " << name << endl; 69 cout << "pass: "; 70 for (int i = 0; i < password.size(); i++) { 71 cout << "*"; 72 } 73 cout << endl; 74 cout << "email " << email << endl; 75 }
1 #define _CRT_SECURE_NO_WARNINGS 1 2 3 #include "user.hpp" 4 #include <iostream> 5 #include <vector> 6 #include <string> 7 8 using std::cin; 9 using std::cout; 10 using std::endl; 11 using std::vector; 12 using std::string; 13 14 void test() { 15 vector<User> user_lst; 16 17 User u1("Alice", "2024113", "Alice@hotmail.com"); 18 user_lst.push_back(u1); 19 cout << endl; 20 21 User u2("Bob"); 22 u2.set_email(); 23 u2.change_password(); 24 user_lst.push_back(u2); 25 cout << endl; 26 27 User u3("Hellen"); 28 u3.set_email(); 29 u3.change_password(); 30 user_lst.push_back(u3); 31 cout << endl; 32 33 cout << "There are " << user_lst.size() << " users. they are: " << endl; 34 for (auto& i : user_lst) { 35 i.display(); 36 cout << endl; 37 } 38 } 39 40 int main() { 41 test(); 42 }
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实验任务6：
代码：
1 #ifndef __DATE_H__ 2 #define __DATE_H__ 3 class Date { private: int year; int month; int day; int totalDays; public: Date(int year, int month, int day); int getYear() const { return year; } int getMonth() const { return month; } int getDay() const { return day; } int getMaxDay() const; bool isLeapYear() const { return year % 4 == 0 && year % 100 != 0 || year % 400 == 0; } void show() const; int distance(const Date& date) const { return totalDays - date.totalDays; } }; #endif //__DATE_H__ #include "date.h" #include <iostream> #include <cstdlib> using namespace std; namespace { const int DAYS_BEFORE_MONTH[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }; } 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(); } #ifndef __ACCOUNT_H__ #define __ACCOUNT_H__ #include "date.h" #include <string> class SavingsAccount { private: std::string id; double balance; double rate; Date lastDate; double accumulation; static double total; void record(const Date &date, double amount, const std::string &desc); void error(const std::string &msg) const; double accumulate(const Date& date) const { return accumulation + balance * date.distance(lastDate); } public: SavingsAccount(const Date &date, const std::string &id, double rate); const std::string &getId() const { return id; } double getBalance() const { return balance; } double getRate() const { return rate; } static double getTotal() { return total; } void deposit(const Date &date, double amount, const std::string &desc); void withdraw(const Date &date, double amount, const std::string &desc); void settle(const Date &date); void show() const; }; #endif //__ACCOUNT_H__ #include "account.h" #include <cmath> #include <iostream> using namespace std; double SavingsAccount::total = 0; 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; 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 << "\tBalance: " << balance; } #include "account.h" #include <iostream> using namespace std; int main() { Date date(2008, 11, 1); SavingsAccount accounts[] = { SavingsAccount(date, "03755217", 0.015), SavingsAccount(date, "02342342", 0.015) }; const int n = sizeof(accounts) / sizeof(SavingsAccount); 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"); cout << endl; for (int i = 0; i < n; i++) { accounts[i].settle(Date(2009, 1, 1)); accounts[i].show(); cout << endl; } cout << "Total: " << SavingsAccount::getTotal() << endl; return 0; }
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