Task1
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 }
View Code
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 }
View Code
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 }
View Code
result1
问题一 这个模拟简单GUI的示例代码中，自定义了几个类？使用到了标准库的哪几个类？，哪些类和类之间存在组合关系？
代码中，自定义了两个类Window，Button。使用了标准库的vector，string类。Window和Button之间，Button和vector之间存在着组合关系
问题二 在自定义类Button和Window中，有些成员函数定义时加了const, 有些设置成了inline。如果你是类的设计者，目前那些没有加const或没有设置成inline的，适合添加const，适合设置成inline吗？陈述你的答案和理由。
const用于保护数据，对于那些不需要改变值的成员函数都应该加上const。inline用于提高程序效率，适合修饰简单，常用的函数。
click也可以设置为inline或者const，因为它实际上只是显示了一行字符串。
问题三 类Window的定义中，有这样一行代码，其功能是？
此代码的功能是构成图形界面的边框。
Task2
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 }
View Code
result2
问题一 测试1模块中，这三行代码的功能分别是？
line21:创建一个储存int的vector对象，初始化有五个元素，每个元素初始化为42。
line22:用v1的数据初始化v2
line23:将v1第0个元素赋值为-999
问题二 测试2模块中，这三行代码的功能分别是？
line32:创建一个二维vector，第一行1,2,3第二行4,5,6,7
line33:用v1的数据来创建v2
line34:在v1的第0行最后加入-999
问题三 测试2模块中，这四行代码的功能分别是？
line39:用v1第0行的数据来创建一个一维vector
line40:输出其最后一个元素
line42:用v2第0行的数据来创建一个一维vector
line43:输出其最后一个元素
问题四
根据执行结果，反向分析、推断：
① 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还是浅复制？
② 模板类vector的接口at(), 是否至少需要提供一个const成员函数作为接口？
1.深复制
2.至少需要提供一个const成员函数作为接口。C++设计原则在于不去扩大权限而保证安全。应当先保证const的，再去重载非const的。
Task3
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 }
View Code
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 }
View Code
result3
问题一vectorInt类中，复制构造函数（line14)的实现，是深复制还是浅复制？
深复制
问题二vectorInt类中，这两个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），测试代码还能正确运行吗？如果把line18返回值类型前面的const掉，针对这个测试代码，是否有潜在安全隐患？尝试分析说明。
修改后程序无法运行，expression must be a modifiable lvalue，变成了一个不可修改的左值。
如果把返回值的const去掉的话，会让const对象调用时，变得可以修改值，且在一些低级的编译器中，可能会无法识别出这个错误。
问题三vectorInt类中，assign()接口，返回值类型可以改成vectorInt吗？你的结论，及，原因分析。
在理论上是可以的，程序可以执行。但是，这样会产生额外开销，特别是vector这样的大对象，需要拷贝构造，生成一个临时的对象。
Task4
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 Matrix::Matrix(int n, int m) : lines{ n }, cols{ m }, ptr{ new double[lines * cols] } {
35 }
36
37 Matrix::Matrix(int n) : Matrix(n, n) {
38 }
39
40 Matrix::Matrix(const Matrix& x) : lines{ x.lines }, cols{ x.cols }, ptr{ new double[x.lines * x.cols] } {
41 for (auto i = 0; i < lines * cols; ++i)
42 ptr[i] = x.ptr[i];
43 }
44
45 Matrix::~Matrix() {
46 delete[] ptr;
47 }
48
49 void Matrix::set(const double* pvalue) {
50 for (auto i = 0; i < lines * cols; ++i)
51 ptr[i] = pvalue[i];
52 }
53
54 void Matrix::clear() {
55 for (auto i = 0; i < lines * cols; ++i)
56 ptr[i] = 0;
57 }
58
59 const double& Matrix::at(int i, int j) const {
60 assert(i >= 0 && i < lines && j >= 0 && j < cols);
61 return ptr[i * cols + j];
62 }
63
64 double& Matrix::at(int i, int j) {
65 assert(i >= 0 && i < lines && j >= 0 && j < cols);
66 return ptr[i * cols + j];
67 }
68
69 inline int Matrix::get_lines() const {
70 return lines;
71 }
72
73 inline int Matrix::get_cols() const {
74 return cols;
75 }
76
77 void Matrix::display() const {
78 for (auto newline = 0; newline < lines; ++newline) {
79 for (int i = 0; i < cols;++i)
80 cout << ptr[newline * cols + i] << " ";
81 cout << endl;
82 }
83 }
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 void test1() {
22 double x[1000] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
23
24 int n, m;
25 cout << "Enter n and m: ";
26 cin >> n >> m;
27
28 Matrix m1(n, m); // 创建矩阵对象m1, 大小n×m
29 m1.set(x); // 用一维数组x的值按行为矩阵m1赋值
30
31 Matrix m2(m, n); // 创建矩阵对象m1, 大小m×n
32 m2.set(x); // 用一维数组x的值按行为矩阵m1赋值
33
34 Matrix m3(2); // 创建一个2×2矩阵对象
35 m3.set(x); // 用一维数组x的值按行为矩阵m4赋值
36
37 cout << "矩阵对象m1: \n"; m1.display(); cout << endl;
38 cout << "矩阵对象m2: \n"; m2.display(); cout << endl;
39 cout << "矩阵对象m3: \n"; m3.display(); cout << endl;
40 }
41
42 void test2() {
43 Matrix m1(2, 3);
44 m1.clear();
45
46 const Matrix m2(m1);
47 m1.at(0, 0) = -999;
48
49 cout << "m1.at(0, 0) = " << m1.at(0, 0) << endl;
50 cout << "m2.at(0, 0) = " << m2.at(0, 0) << endl;
51 cout << "矩阵对象m1第0行: "; output(m1, 0);
52 cout << "矩阵对象m2第0行: "; output(m2, 0);
53 }
54
55 int main() {
56 cout << "测试1: \n";
57 test1();
58
59 cout << "测试2: \n";
60 test2();
61 }
View Code
result4
Task5
User.hpp
1 #pragma once
2
3 #include <iostream>
4 #include <vector>
5 #include <iomanip>
6
7 using std::string;
8 using std::cout;
9 using std::cin;
10 using std::endl;
11 using std::setw;
12 using std::left;
13
14 class User {
15 public:
16 User(string user_name, string user_password = "123456", string user_email = "");
17 ~User() = default;
18
19 void set_email();
20 void change_password();
21 void display() const;
22
23 private:
24 string name;
25 string password;
26 string email;
27 };
28
29 User::User(string user_name, string user_password, string user_email) {
30 name = user_name;
31 password = user_password;
32 email = user_email;
33 }
34
35 void User::set_email() {
36 string temp;
37 cout << "Enter email address: ";
38
39 while (cin >> temp) {
40 if (temp.find('@') != std::string::npos) {
41 cout << "email is set successfully..." << endl;
42 email = temp;
43 break;
44 }
45 else {
46 cout << "illegal email. Please re-enter email: ";
47 }
48 }
49 }
50
51 void User::change_password() {
52 string temp;
53 int count = 0;
54
55 cout << "Enter old password: ";
56 while (cin >> temp) {
57
58
59 if (temp == password) {
60 cout << "Enter new password: ";
61 cin >> temp;
62 password = temp;
63 cout << "new password is set successfully..." << endl;
64 break;
65 }
66 else {
67 cout << "password input error. Please re-enter again ";
68 count++;
69 if (count >= 3) {
70 cout << "password input error. Please try after a while." << endl;
71 break;
72 }
73 }
74 }
75 }
76
77 void User::display() const {
78 cout << setw(8) << left << "name: " << name << endl;
79
80 string show_password;
81 for (auto i = 0; i < password.size(); ++i) show_password += '*';
82 cout << setw(8) << left << "pass: " << show_password << endl;
83
84 cout << setw(8) << left << "email: " << email << endl;
85
86 }
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", "[email protected]");
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 int main() {
38 test();
39 }
View Code
result5
Task6
date.hpp
1 #pragma once
2
3 #include<iostream>
4 #include<cstdlib>
5
6 using namespace std;
7 class Date {
8 private:
9 int year;
10 int month;
11 int day;
12 int totalDays;
13 public:
14 Date(int year, int month, int day);
15 int getYear()const {
16 return year;
17 }
18 int getMonth()const {
19 return month;
20 }
21 int getDay()const {
22 return day;
23 }
24 int getMaxDay()const;
25 bool isLeapYear()const {
26 return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
27 }
28 void show() const;
29 int distance(const Date& date)const {
30 return totalDays - date.totalDays;
31 }
32 };
33 namespace {
34 const int DAYS_BEFIRE_MONTH[] = { 0,31,59,90,120,151,181,212,243,273,304 ,334,365 };
35 }
36 Date::Date(int year, int month, int day) :year(year), month(month), day(day) {
37 if (day <= 0 || day > getMaxDay()) {
38 cout << "Invalid date: ";
39 show();
40 cout << endl;
41 exit(1);
42 }
43 int years = year - 1;
44 totalDays = years * 365 + years / 4 - years / 100 + years / 400 + DAYS_BEFIRE_MONTH[month - 1] + day;
45 if (isLeapYear() && month > 2) totalDays++;
46 }
47 int Date::getMaxDay()const {
48 if (isLeapYear() && month == 2)
49 return 29;
50 else return DAYS_BEFIRE_MONTH[month] - DAYS_BEFIRE_MONTH[month - 1];
51 }
52 void Date::show()const {
53 cout << getYear() << "-" << getMonth() << "-" << getDay();
54 }
View Code
account.hpp
1 #pragma once
2
3 #include"date.hpp"
4 #include<string>
5 #include<cmath>
6 #include<iostream>
7
8 using namespace std;
9
10 class SavingsAccount {
11 private:
12 string id;
13 double balance;
14 double rate;
15 Date lastDate;
16 double accumulation;
17 static double total;
18 void record(const Date& date, double amount, const string& desc);
19 void error(const string& msg) const;
20 double accumulate(const Date& date)const {
21 return accumulation + balance * date.distance(lastDate);
22 }
23 public:
24 SavingsAccount(const Date& date, const string& id, double rate);
25 const string& getId()const {
26 return id;
27 }
28 double getBalance()const {
29 return balance;
30 }
31 double getRate()const {
32 return rate;
33 }
34 static double getTotal() {
35 return total;
36 }
37 void deposit(const Date& date, double amount, const string& desc);
38 void withdraw(const Date& date, double amount, const string& desc);
39 void settle(const Date& date);
40 void show() const;
41 };
42 double SavingsAccount::total = 0;
43 SavingsAccount::SavingsAccount(const Date& date, const string& id, double rate) :
44 id(id), balance(0), rate(rate), lastDate(date), accumulation(0) {
45 date.show();
46 cout << "\t#" << id << "created" << endl;
47 }
48 void SavingsAccount::record(const Date& date, double amount, const string& desc) {
49 accumulation = accumulate(date);
50 lastDate = date;
51 amount = floor(amount * 100 + 0.5) / 100;
52 balance += amount;
53 total += amount;
54 date.show();
55 cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
56 }
57 void SavingsAccount::error(const string& msg) const {
58 cout << "Error(#" << id << "):" << msg << endl;
59 }
60 void SavingsAccount::deposit(const Date& date, double amount, const string& desc) {
61 record(date, amount, desc);
62 }
63 void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) {
64 if (amount > getBalance())
65 error("not enough money");
66 else
67 record(date, -amount, desc);
68 }
69 void SavingsAccount::settle(const Date& date) {
70 double interest = accumulate(date) * rate / date.distance(Date(date.getYear() - 1, 1, 1));
71 if (interest != 0) record( date,interest,"interest" );
72 accumulation = 0;
73 }
74 void SavingsAccount::show()const {
75 cout << id << "\tBalance: " << balance;
76 }
View Code
result6
标签：const,string,对象,编程,int,实验,vectorInt,include,cout From： https://www.cnblogs.com/nuist0415/p/18525597