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", "[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 }
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 }
标签：std,const,string,int,实验,include,cout From： https://www.cnblogs.com/-transparent/p/18525727