task1.cpp
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 }
button.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 }
window.hpp
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 }
task1.cpp
问题1：自定义了两个类，分别是Window和Button。使用了标准库中的iostream、string、vector类。Window和Button之间存在组合关系。
问题2：click适合设置成inline，inline函数小，设置成内联可以减少跳转。
问题3：创建了一个长度为 40 的字符串，其中每个位置都被字符 '*' 填充。结果是一个包含 40 个星号的字符串。
运行结果截图：
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 v1.at(0) = -999;
24 cout << "v1: "; output1(v1);
25 cout << "v2: "; output1(v2);
26 cout << "v1.at(0) = " << v1.at(0) << endl;
27 cout << "v2.at(0) = " << v2.at(0) << endl;
28 }
29
30 void test2() {
31 vector<vector<int>> v1{ {1, 2, 3}, {4, 5, 6, 7} };
32 const vector<vector<int>> v2(v1);
33 v1.at(0).push_back(-999);
34 cout << "v1: \n"; output2(v1);
35 cout << "v2: \n"; output2(v2);
36 vector<int> t1 = v1.at(0);
37 cout << t1.at(t1.size() - 1) << endl;
38 const vector<int> t2 = v2.at(0);
39 cout << t2.at(t2.size() - 1) << endl;
40 }
41 int main() {
42 cout << "测试1:\n";
43 test1();
44 cout << "\n测试2:\n";
45 test2();
46 }
task2.cpp
问题1：v1是一个包含5个元素的可变大小数组，每个元素的值都是42。v2通过复制构造函数用v1的内容来初始化它。由于v2被声明为const，它的内容在创建后就不能被修改。v3使用at成员函数来访问v1中的第一个元素，并将其值更改为-999。
问题2：v1是一个二维向量，包含两个元素：第一个元素是一个包含1, 2, 3的vector<int>，第二个元素是一个包含4, 5, 6, 7的vector<int>。v2是由v1初始化的不可修改的对象。这行代码通过at成员函数访问v1中的第一个元素，并调用push_back成员函数添加一个值为-999的新元素。
问题3：
vector<int> t1 = v1.at(0);这行代码从v1中获取索引为0的vector<int>元素{1，2，3，-999}，并将其复制到一个新的对象t1中。
cout << t1.at(t1.size() - 1) << endl;这行代码使用at成员函数访问t1中的最后一个元素，这行代码将输出-999。
const vector<int> t2 = v2.at(0);这行代码从v2中获取索引为0的元素，并将其复制到一个新的常量vector<int>对象t2中。由于v2是const的，并且它是通过复制v1的初始状态来创建的，所以t2是{1, 2, 3}。
cout << t2.at(t2.size() - 1) << endl;这行代码输出3；
问题4：①深复制 ②需要提供一个const成员函数作为接口。
运行结果截图：
task3.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 }
vectorInt.hpp
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 }
task3.cpp
问题1：深复制，新对象分配了一个与原始对象 vi 相同大小的整数数组，并逐个复制 vi.ptr 数组中的元素到新对象的 ptr 数组中
问题2：如果将at()方法的返回值类型从int&和const int&更改为int，则这些方法将返回数组元素的副本，而不是元素的直接引用。调用者将无法通过at()方法修改数组中的值，因为返回的是值的副本。
问题3：如果将assign()方法的返回值类型从vectorInt&更改为vectorInt，返回当前对象的一个副本。这样复制整个数组，造成了不必要的开销。
运行结果截图：
task4.cpp
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[n * m]()) {
35 // 初始化一个n*m的矩阵，所有元素为0
36 for (int i = 0; i < n * m; ++i) {
37 ptr[i] = 0;
38 }
39 }
40
41 Matrix::Matrix(int n) : Matrix(n, n) {} // 调用另一个构造函数实现n*n矩阵
42
43 Matrix::Matrix(const Matrix& x) : lines(x.lines), cols(x.cols), ptr(new double[x.lines * x.cols]) {
44 // 复制构造函数
45 for (int i = 0; i < lines * cols; ++i) {
46 ptr[i] = x.ptr[i];
47 }
48 }
49
50 Matrix::~Matrix() {
51 delete[] ptr; // 释放内存
52 }
53
54 void Matrix::set(const double* pvalue) {
55 int k = 0;
56 for (int i = 0; i < lines; ++i) {
57 for (int j = 0; j < cols; ++j) {
58 ptr[i * cols + j] = pvalue[k++];
59 }
60 }
61 }
62
63 void Matrix::clear() {
64 for (int i = 0; i < lines * cols; ++i) {
65 ptr[i] = 0;
66 }
67 }
68
69 const double& Matrix::at(int i, int j) const {
70 assert(i >= 0 && i < lines && j >= 0 && j < cols);
71 return ptr[i * cols + j];
72 }
73
74 double& Matrix::at(int i, int j) {
75 assert(i >= 0 && i < lines && j >= 0 && j < cols);
76 return ptr[i * cols + j];
77 }
78
79 int Matrix::get_lines() const {
80 return lines;
81 }
82
83 int Matrix::get_cols() const {
84 return cols;
85 }
86
87 void Matrix::display() const {
88 for (int i = 0; i < lines; ++i) {
89 for (int j = 0; j < cols; ++j) {
90 cout << ptr[i * cols + j] << " ";
91 }
92 cout << endl;
93 }
94 }
matrix.hpp
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 }
task4.cpp
运行结果截图：
task5.cpp
1 #ifndef USER_HPP
2 #define USER_HPP
3
4 #include <string>
5 #include <iostream>
6
7 class User {
8 private:
9 std::string name;
10 std::string password;
11 std::string email;
12
13 public:
14 // 构造函数
15 User(const std::string& uname)
16 : name(uname), password("123456"), email("") {}
17
18 User(const std::string& uname, const std::string& pwd, const std::string& eml)
19 : name(uname), password(pwd), email(eml) {}
20
21 // 设置邮箱
22 void set_email() {
23 std::string input;
24 bool valid = false;
25 int attempts = 0;
26
27 while (!valid && attempts < 3) {
28 std::cout << "Enter email address: ";
29 std::cin >> input;
30
31 if (input.find('@') != std::string::npos) {
32 valid = true;
33 email = input;
34 }
35 else {
36 std::cout << "illegal email.Please re-enter email:" << std::endl;
37 attempts++;
38 }
39 }
40
41 if (attempts == 3) {
42 std::cout << "password input error.Please try after a while." << std::endl;
43 }
44 }
45
46 // 修改密码
47 void change_password() {
48 std::string old_pwd, new_pwd;
49 bool valid = false;
50 int attempts = 0;
51
52 while (!valid && attempts < 3) {
53 std::cout << "Enter old password: ";
54 std::cin >> old_pwd;
55
56 if (old_pwd == password) {
57 valid = true;
58 break;
59 }
60 else {
61 std::cout << "password input error.Please re-enter again:" << std::endl;
62 attempts++;
63 }
64 }
65
66 if (valid) {
67 std::cout << "Enter new password: ";
68 std::cin >> new_pwd;
69 password = new_pwd;
70 }
71 else {
72 std::cout << "password input error.Please try after a while." << std::endl;
73 }
74 }
75
76 // 显示用户信息
77 void display() const {
78 std::cout << "name: " << name << std::endl;
79 std::cout << "pass: ";
80 for (char ch : password) {
81 std::cout << '*';
82 }
83 std::cout << std::endl;
84 std::cout << "email: " << email << std::endl;
85 }
86 };
87
88 #endif // USER_HPP
user.hpp
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
38 int main() {
39 test();
40 }
task5.cpp
运行结果截图：
task6.cpp:
1 #ifndef __DATE_H__
2 #define __DATE_H__
3 class Date {
4 private:
5 int year;
6 int month;
7 int day;
8 int totalDays;
9 public:
10 Date(int year, int month, int day);
11 int getYear()const { return year; }
12 int getMonth()const { return month; }
13 int getDay()const { return day; }
14 int getMaxDay()const;
15 bool isLeapYear()const {
16 return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
17 }
18 void show()const;
19 int distance(const Date& date)const {
20 return totalDays - date.totalDays;
21 }
22 };
23 #endif//__DATE_H__
date.h
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 }
date.cpp
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 public:
19 SavingsAccount(const Date& date, const std::string& id, double rate);
20 const std::string& getID()const { return id; }
21 double getBalance()const { return balance; }
22 double getRate()const { return rate; }
23 static double getTotal() {
24 return total;
25 }
26 void deposit(const Date& date, double amount, const std::string& desc);
27 void withdraw(const Date& date, double amount, const std::string& desc);
28 void settle(const Date& date);
29 void show()const;
30 };
31 #endif //__ACCOUNT_H__
account.h
1 #include "account.h"
2 #include<cmath>
3 #include<iostream>
4 using namespace std;
5 double SavingsAccount::total = 0;
6 SavingsaAccount::SavingsAccount(const Date& date, const string& id, double rate) :id(id), balance(0), rate(rate), lastDate(date), accumulation(0) {
7 date.show();
8 cout << "\t#" << id << "created" << endl;
9 }
10 void SavingsAccount::record(const Date& date, double amount, const string& desc) {
11 accumulation = accumulate(date);
12 lastDate = date;
13 amount = floor(amount * 100 + 0.5) / 100;
14 balance += amount;
15 total += amount;
16 date.show();
17 cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
18 }
19 void SavingsAccount::error(const string& msg)const {
20 cout << "Error(#" << id << "):" << msg << endl;
21 }
22 void SavingsAccount::deposit(const Date& date, double amount, const string& desc) {
23 record(date, amount, desc);
24 }
25 void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) {
26 if (amount > getBalance())
27 error("not enough money");
28 else
29 record(date, -amount, desc);
30 }
31 void SavingsAccount::settle(const Date& date) {
32 double interest = accumulate(date) * rate / date.distance(Date(date.getYear() - 1, 1, 1));
33 if (interest != 0)
34 record(date, interest, "interest");
35 accumulation = 0;
36 }
37 void SavingsAccount::show()const {
38 cout << id << "\tBalance:" << balance;
39 }
account.cpp
1 #include"account.h"
2 #include<iostream>
3 using namespace std;
4 int main() {
5 Date date(2008, 11, 1);
6 SavingsAccount accounts[] = { SavinsAccount(date,"03755217",0.015),SavingsAccount(date,"02342342",0.015) };
7 const int n = sizeof(accounts) / sizeof(SavingsAccount);
8 accounts[0].deposit(Date(2008, 11, 5), 5000, "salary");
9 accounts[0].deposit(Date(2008, 11, 25), 10000, "sell stock 0323");
10 accounts[0].deposit(Date(2008, 12, 5), 5500, "salary");
11 accounts[0].withdraw(Date(2008, 12, 20), 4000, "buy a laptop");
12 cout << endl;
13 for (int i = 0; i < n; i++) {
14 accounts[i].settle(Date(2009, 1, 1));
15 accounts[i].show();
16 cout << endl;
17 }
18 cout << "Total:" << SavinsAccount::getTotal() << endl;
19 return 0;
20 }
6_25.cpp
运行结果截图：
