OOP實驗三

孙一发發表於2024-11-10
OOP

任務1：

原始碼：

 1 #pragma once
 2 
 3 #include <iostream>
 4 #include <string>
 5 
 6 using std::string;
 7 using std::cout;
 8 
 9 // 按鈕類
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 // 視窗類
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 << "用組合類模擬簡單GUI:\n";
16     test();
17 }

結果：

回答：

問題1：這個模擬簡單GUI的示例程式碼中，自定義了幾個類？使用到了標準庫的哪幾個類？，
哪些類和類之間存在組合關係？
兩個類，
vector，
button類是vector中的元素，該vector是window類的成員。
問題2：在自定義類Button和Window中，有些成員函式定義時加了const, 有些設定成了
inline。如果你是類的設計者，目前那些沒有加const或沒有設定成inline的，適合新增const，
適合設定成inline嗎？你的思考依據是？
Button::click和Window::close不適合加inline,在實際專案中該函式執行的內容較複雜，不必新增const，因為沒有資料的傳輸。
Window::add不適合加inline，需要更改物件內容。
問題3：類Window的定義中，有這樣一行程式碼，其功能是？
視窗分隔線。

任務2：

原始碼：

 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 << "    1:\n";
48     test1();
49 
50     cout << "\n    2:\n";
51     test2();
52 }

結果：

答：

問題1：測試1模組中，這三行程式碼的功能分別是？
構造大小為5，元素值為42的vector物件。
利用v1複製構造v2。
將v1的第一個值改為-999.
問題2：測試2模組中，這三行程式碼的功能分別是？
構造以vector物件為元素的vector物件。
利用v1複製構造v2。
獲取v1中的第一個vector物件元素，並在該物件末尾增加元素-999。
問題3：測試2模組中，這四行程式碼的功能分別是？
將v1中第一個元素值付給t1的第一個元素。
輸出t1的最後一個元素值。
將v2中第一個元素值付給t2的第一個元素。
輸出t2的最後一個元素值。
問題4：根據執行結果，反向分析、推斷：
① 標準庫模板類vector內部封裝的複製建構函式，其實現機制是深複製還是淺複製？
深複製
② 模板類vector的介面at(), 是否至少需要提供一個const成員函式作為介面？
是

任務3：

原始碼：

 1 #pragma once
 2 
 3 #include <iostream>
 4 #include <cassert>
 5 
 6 using std::cout;
 7 using std::endl;
 8 
 9 // 動態int陣列物件類
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個int的陣列
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;       // 釋放物件中ptr原來指向的資源
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 << "測試1: \n";
45     test1();
46 
47     cout << "\n測試2: \n";
48     test2();
49 }

結果：

答：

問題1：vectorInt類中，複製建構函式（line14)的實現，是深複製還是淺複製？
深複製
問題2：vectorInt類中，這兩個at()介面，如果返回值型別改成int而非int&（相應地，實現部
分也同步修改），測試程式碼還能正確執行嗎？
能
如果把line18返回值型別前面的const掉，針對
這個測試程式碼，是否有潛在安全隱患？嘗試分析說明。
有，內部元素值會被修改。
問題3：vectorInt類中，assign()介面，返回值型別可以改成vectorInt嗎？你的結論，及，原
因分析。
不能，增加了複製開銷。

任務4：

原始碼：

  1 #pragma once
  2 
  3 #include <iostream>
  4 #include <cassert>
  5 
  6 using std::cout;
  7 using std::endl;
  8 
  9 // 類Matrix的宣告
 10 class Matrix {
 11 public:
 12     Matrix(int n, int m);           // 建構函式，構造一個n*m的矩陣, 初始值為value
 13     Matrix(int n);                  // 建構函式，構造一個n*n的矩陣, 初始值為value
 14     Matrix(const Matrix &x);        // 複製建構函式， 使用已有的矩陣X構造
 15     ~Matrix();
 16 
 17     void set(const double *pvalue);         // 用pvalue指向的連續記憶體塊資料按行為矩陣賦值
 18     void clear();                           // 把矩陣物件的值置0
 19     
 20     const double& at(int i, int j) const;   // 返回矩陣物件索引(i,j)的元素const引用
 21     double& at(int i, int j);               // 返回矩陣物件索引(i,j)的元素引用
 22     
 23     int get_lines() const;                  // 返回矩陣物件行數
 24     int get_cols() const;                   // 返回矩陣物件列數
 25 
 26     void display() const;                    // 按行顯示矩陣物件元素值
 27 
 28 private:
 29     int lines;      // 矩陣物件內元素行數
 30     int cols;       // 矩陣物件內元素列數
 31     double *ptr;
 32 };
 33 
 34 // 類Matrix的實現：待補足
 35 Matrix::Matrix(int n, int m) {
 36     lines = n;
 37     cols = m;
 38     ptr = (double*)malloc(sizeof(double) * n * m);
 39 }
 40 Matrix::Matrix(int n) {
 41     lines = n;
 42     cols = n;
 43     ptr = (double*)malloc(sizeof(double) * n * n);
 44 }
 45 Matrix::Matrix(const Matrix& x) {
 46     lines = x.get_lines();
 47     cols = x.get_cols();
 48     ptr = (double*)malloc(sizeof(double) * lines * cols);
 49     int i, j;
 50     int line = x.get_lines();
 51     int col = x.get_cols();
 52     for (i = 0; i < line; i++) {
 53         for (j = 0; j < col; j++) {
 54             *(ptr + cols * i + j) = *(x.ptr + cols * i + j);
 55         }
 56     }
 57 }
 58 Matrix::~Matrix() {
 59 
 60 }
 61 int Matrix::get_lines() const {
 62     return lines;
 63 }
 64 int Matrix::get_cols()const {
 65     return cols;
 66 }
 67 void Matrix::set(const double* pvalue) {
 68     int i, j;
 69     int line = get_lines();
 70     int col = get_cols();
 71     for (i = 0; i < line; i++) {
 72         for (j = 0; j < col; j++) {
 73             *(ptr + cols * i + j) = *(pvalue + cols * i + j);
 74         }
 75     }
 76 }
 77 void Matrix::clear() {
 78     int i, j;
 79     int line = get_lines();
 80     int col = get_cols();
 81     for (i = 0; i < line; i++) {
 82         for (j = 0; j < col; j++) {
 83             *(ptr + cols * i + j) = 0;
 84         }
 85     }
 86 }
 87 const double& Matrix::at(int i, int j) const {
 88     return *(ptr + cols * i + j);
 89 }
 90 double& Matrix::at(int i, int j) {
 91     return *(ptr + cols * i + j);
 92 }
 93 void Matrix::display() const {
 94     int i, j;
 95     int line = get_lines();
 96     int col = get_cols();
 97     for (i = 0; i < line; i++) {
 98         for (j = 0; j < col; j++) {
 99             cout << *(ptr + cols * i + j);
100             if (j != col - 1) {
101                 cout << ",";
102             }
103         }
104         cout << endl;
105     }
106 }
107 
108 
109 
110 
111 #include "matrix.hpp"
112 #include <iostream>
113 #include <cassert>
114 
115 using std::cin;
116 using std::cout;
117 using std::endl;
118 
119 
120 const int N = 1000;
121 
122 // 輸出矩陣物件索引為index所在行的所有元素
123 void output(const Matrix &m, int index) {
124     assert(index >= 0 && index < m.get_lines());
125 
126     for(auto j = 0; j < m.get_cols(); ++j)
127         cout << m.at(index, j) << ", ";
128     cout << "\b\b \n";
129 }
130 
131 
132 void test1() {
133     double x[1000] = {11, 12, 13, 14, 15, 16, 17, 18, 19};
134 
135     int n, m;
136     cout << "Enter n and m: ";
137     cin >> n >> m;
138 
139     Matrix m1(n, m);    // 建立矩陣物件m1, 大小n×m
140     m1.set(x);          // 用一維陣列x的值按行為矩陣m1賦值
141 
142     Matrix m2(m, n);    // 建立矩陣物件m1, 大小m×n
143     m2.set(x);          // 用一維陣列x的值按行為矩陣m1賦值
144 
145     Matrix m3(2);       // 建立一個2×2矩陣物件
146     m3.set(x);          // 用一維陣列x的值按行為矩陣m4賦值
147 
148     cout << "矩陣物件m1: \n";   m1.display();  cout << endl;
149     cout << "矩陣物件m2: \n";   m2.display();  cout << endl;
150     cout << "矩陣物件m3: \n";   m3.display();  cout << endl;
151 }
152 
153 void test2() {
154     Matrix m1(2, 3);
155     m1.clear();
156     
157     const Matrix m2(m1);
158     m1.at(0, 0) = -999;
159 
160     cout << "m1.at(0, 0) = " << m1.at(0, 0) << endl;
161     cout << "m2.at(0, 0) = " << m2.at(0, 0) << endl;
162     cout << "矩陣物件m1第0行: "; output(m1, 0);
163     cout << "矩陣物件m2第0行: "; output(m2, 0);
164 }
165 
166 int main() {
167     cout << "測試1: \n";
168     test1();
169 
170     cout << "測試2: \n";
171     test2();
172 }

結果：

任務5：

原始碼：

  1 #include <iostream>
  2 #include <vector>
  3 #include <string>
  4 using namespace std;
  5 class User {
  6 private:
  7     string name;
  8     string password;
  9     string email;
 10 public:
 11     User(string n);
 12     User(string n, string pw, string em);
 13     ~User();
 14     void set_email();
 15     void change_password();
 16     void display()const;
 17 };
 18 User::User(string n){
 19     name = n;
 20     password = "123456";
 21     email = "";
 22 }
 23 User::User(string n, string pw, string em) {
 24     name = n;
 25     password = pw;
 26     email = em;
 27 }
 28 User::~User() {}
 29 void User::set_email() {
 30     cout << "Enter email address:";
 31     string em;
 32     while (1) {
 33         cin >> em;
 34         if (em.find('@') == -1) {
 35             cout << "illegal email.Please re-enter email:";
 36             continue;
 37         }
 38         email = em;
 39         cout << "email is set successfully." << endl;
 40         break;
 41     }
 42 }
 43 void User::change_password() {
 44     cout << "Enter old password:";
 45     string opw;
 46     int cnt = 0;
 47     while (1) {
 48         cin >> opw;
 49         if (opw.compare(password)) {
 50             cnt++;
 51             if (cnt >= 3) {
 52                 cout << "Try again later." << endl;
 53                 break;
 54             }
 55             cout << "Wrong.Please enter the true old password:";
 56             continue;
 57         }
 58         cout << "Enter new password:";
 59         cin >> password;
 60         cout << "new password is set successfully." << endl;
 61         break;
 62     }
 63 }
 64 void User::display()const {
 65     cout << "name:" << name << endl;
 66     int i;
 67     cout << "pass:";
 68     for (i = 0; i < password.size(); i++) {
 69         cout << '*';
 70     }
 71     cout << endl;
 72     cout << "email:" << email << endl << endl;
 73 }
 74 
 75 
 76 
 77 #include "user.hpp"
 78 #include <iostream>
 79 #include <vector>
 80 #include <string>
 81 
 82 using std::cin;
 83 using std::cout;
 84 using std::endl;
 85 using std::vector;
 86 using std::string;
 87 
 88 void test() {
 89     vector<User> user_lst;
 90 
 91     User u1("Alice", "2024113", "Alice@hotmail.com");
 92     user_lst.push_back(u1);
 93     cout << endl;
 94 
 95     User u2("Bob");
 96     u2.set_email();
 97     u2.change_password();
 98     user_lst.push_back(u2);
 99     cout << endl;
100 
101     User u3("Hellen");
102     u3.set_email();
103     u3.change_password();
104     user_lst.push_back(u3);
105     cout << endl;
106 
107     cout << "There are " << user_lst.size() << " users. they are: " << endl;
108     for (auto& i : user_lst) {
109         i.display();
110         cout << endl;
111     }
112 }
113 
114 int main() {
115     test();
116 }

結果：

任務6：

原始碼：

 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     }
19 public:
20     SavingsAccount(const Date& date, const std::string& id, double rate);
21     const std::string& getId()const { return id; }
22     double getBalance()const { return balance; }
23     double getRate()const { return rate; }
24     static double getTotal() { return total; }
25     void deposit(const Date& date, double amount, const std::string& desc);
26     void withdraw(const Date& date, double amount, const std::string& desc);
27     void settle(const Date& date);
28     void show()const;
29 };
30 #endif //_ _ACCOUNT_H_ _
 1 class Date {
 2 private:
 3     int year;
 4     int month;
 5     int day;
 6     int totalDays;
 7 public:
 8     Date(int year, int month, int day);
 9     int getYear() const { return year; }
10     int getMonth()const { return month; }
11     int getDay()const { return day; }
12     int getMaxDay()const;
13     bool isLeapYear()const {
14         return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
15     }
16     void show() const;
17     int distance(const Date& date)const {
18         return totalDays - date.totalDays;
19     }
20 };
 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)
 7     :id(id), balance(0), rate(rate), lastDate(date), accumulation(0) {
 8     date.show();
 9     cout << "\t#" << id << "created" << endl;
10 
11 }
12 void SavingsAccount::record(const Date& date, double amount, const string& desc) {
13     accumulation = accumulate(date);
14     lastDate = date;
15     amount = floor(amount * 100 + 0.5) / 100;
16     balance -= amount;
17     total += amount;
18     date.show();
19     cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
20 
21 }
22 void SavingsAccount::error(const string& msg)const {
23     cout << "Error(#" << id << "):" << msg << endl;
24 }
25 void SavingsAccount::deposit(const Date& date, double  amount, const string& desc) {
26     record(date, amount, desc);
27 }
28 void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) {
29     if (amount > getBalance())
30         error("not enough money");
31     else
32         record(date, -amount, desc);
33 
34 }
35 void SavingsAccount::settle(const Date& date) {
36     double interest = accumulate(date) * rate
37         / date.distance(Date(date.getYear() - 1, 1, 1));
38     if (interest != 0)
39         record(date, interest, "interest");
40     accumulation = 0;
41 
42 }
43 void SavingsAccount::show()const {
44     cout << id << "\tBalance:" << balance;
45 }
 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 #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     };
11     const int n = sizeof(accounts) / sizeof(SavingsAccount);
12     accounts[0].deposit(Date(2008, 11, 5), 5000, "salary");
13     accounts[1].deposit(Date(2008, 11, 25), 10000, "sell stock 0323");
14     accounts[0].deposit(Date(2008, 12, 5), 5500, "salary");
15     accounts[1].withdraw(Date(2008, 12, 20), 4000, "buy a laptop");
16     cout << endl;
17     for (int i = 0; i < n; i++) {
18         accounts[i].settle(Date(2009, 1, 1));
19         accounts[i].show();
20         cout << endl;
21     }
22     cout << "Total:" << SavingsAccount::getTotal() << endl;
23     return 0;
24 }

結果：

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