实验任务1：
代码：
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 }
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 }
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 }
运行结果截图：
回答问题：
问题1：自定义了两个类，使用到了标准库的vector类，自定义的Button类和vector之间存在组合关系、vector
和自定义的Window类之间存在组合关系
问题2：有一些，如add_button，涉及到数据改变的，不能设置为const成员函数。在已经添加了inline的函数之外，其余函数的操作都很简单，没有必要设置为inline。
问题3：字符串s = 40个*
实验任务2：
代码：
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 }
运行结果截图：
回答问题：
问题1：21行构造了一个名字为v1的vctor<int>动态数组，并且v1在构造时同时初始化，存放了5个42。22行借助v1复制构造了v2。24行调用at()，把v1的第0项赋值为-999。
问题2：32行构造了一个名字为v1的二维vctor动态数组，并且v1在构造时同时初始化。22行借助v1复制构造了v2，v2是const常量。35行调用at()和push_back()，在v1的第0行的末尾追加了一个数-999。
问题3：39行构造了一个vector<int>动态数组t1，并用二维数组v1的第零行初始化。40行输出t1最后一个数据。42行构造了一个const vector<int>的对象t2，并用v2的第零行初始化。第43行输出t2的最后一个数据。
问题4：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。模板类vector的接口at(), 不需要至少提供一个const成员函数作为接口。
实验任务3：
代码：
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 }
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 }
运行结果截图：
回答问题：
问题1：深复制
问题2：vectorInt类中，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），测试代码不能正确运行。因为测试代码中x2.at(0) = -999这样的调用，表明需要修改x2内部的值，所以返回值必须是int&。如果把line18返回值类型前面的const去掉，针对这个测试代码，有潜在安全隐患。因为在test2中存在const vectorInt x(5, 42)，所以去掉后会报错。
问题3：在目前的测试代码中，这样修改没有问题。
实验任务4：
代码：
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：
35 Matrix::Matrix(int n, int m) : lines{ n }, cols{ m } {
36 ptr = new double[n * m];
37 }
38
39 Matrix::Matrix(int n) : lines{ n }, cols{ n } {
40 ptr = new double[n * n];
41 }
42
43 Matrix::Matrix(const Matrix& x) : lines{ x.lines }, cols{x.cols} {
44 ptr = new double[x.lines * x.cols];
45 for (auto i = 0; i < x.lines * x.cols; i++)
46 *(ptr + i) = *(x.ptr + i);
47 }
48
49 Matrix::~Matrix() {}
50
51 void Matrix::set(const double* pvalue) {
52 for (auto i = 0; i < lines * cols; i++)
53 *(ptr + i) = *(pvalue + i);
54 }
55
56 void Matrix::clear() {
57 for (auto i = 0; i < lines * cols; i++)
58 *(ptr + i) = 0;
59 }
60
61 const double& Matrix::at(int i, int j) const {
62 return *(ptr + lines * i + j);
63 }
64
65 double& Matrix::at(int i, int j) {
66 return *(ptr + lines * i + j);
67 }
68
69 int Matrix::get_lines() const {
70 return lines;
71 }
72
73 int Matrix::get_cols() const {
74 return cols;
75 }
76
77 void Matrix::display() const {
78 for (auto i = 0; i < lines; i++) {
79 for (auto j = 0; j < cols; j++) {
80 cout << *(ptr + i * cols + j) << ", ";
81 cout << "\b\b ";
82 }
83 cout << endl;
84 }
85 }
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 }
测试结果截图：
实验任务5：
代码：
user.hpp
1 #pragma once
2 #include <iostream>
3 #include <iomanip>
4
5 using namespace std;
6
7 class User {
8 public:
9 User(string n, string p = "123456", string e = "\0");
10
11 void set_email();
12 void change_password();
13 void display() const;
14
15 bool check_email(string e);
16
17 private:
18 string name;
19 string password;
20 string email;
21 };
22
23 User::User(string n, string p, string e) : name{ n }, password{ p }, email{ e } {
24
25 }
26
27 bool User::check_email(string e) {
28 auto pos = e.find("@");
29 if (pos == e.npos) {
30 cout << "illegal email. Please re-enter email: ";
31 return false;
32 }
33 else {
34 cout << "email is set successfully..." << endl;
35 return true;
36 }
37 }
38
39 void User::set_email() {
40 cout << "Enter email address: ";
41 string e;
42 cin >> e;
43
44 if (check_email(e))
45 email = e;
46 else
47 set_email();
48 }
49
50 void User::change_password() {
51 cout << "Enter old password: ";
52 string p;
53 cin >> p;
54
55 int i = 1;
56 for (; i <= 3; i++) {
57 if (p == password) {
58 cout << "Enter new password: ";
59 cin >> password;
60 cout << "new password is set successfully..." << endl;
61 break;
62 }
63 else if (p != password && i == 3)
64 cout << "password input error. Please try after a while." << endl;
65 else {
66 cout << "password input error. Please re-enter again: ";
67 cin >> p;
68 }
69 }
70 }
71
72 void User::display() const {
73 cout << setiosflags(ios::left) << setw(10) << "name:" << name << endl;
74 string p(password.size(), '*');
75 cout << setiosflags(ios::left) << setw(10) << "pass:" << p << endl;
76 cout << setiosflags(ios::left) << setw(10) << "email:" << email << endl;
77 }
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 }
运行结果截图：
实验任务6：
date.h
1 #pragma once
2
3 class Date {
4 private:
5 int year;
6 int month;
7 int day;
8 int totalDays;
9
10 public:
11 Date(int year, int month, int day);
12 int getYear() const { return year; }
13 int getMonth() const { return month; }
14 int getDay() const { return day; }
15 int getMaxDay() const;
16 bool isLeapYear() const {
17 return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
18 }
19 void show() const;
20 int distance(const Date& date) const {
21 return totalDays - date.totalDays;
22 }
23 };
date.cpp
1 #include "date.h"
2 #include <iostream>
3 #include <cstdlib>
4
5 using namespace std;
6
7 namespace {
8 const int DAYS_BEFORE_MONTH[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
9 }
10
11 int Date::getMaxDay() const {
12 if (isLeapYear() && month == 2)
13 return 29;
14 else
15 return DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1];
16 }
17
18 void Date::show() const{
19 cout << getYear() << "-" << getMonth() << "-" << getDay();
20 }
21
22 Date::Date(int year, int month, int day) : year{ year }, month{ month }, day{ day } {
23 if (day <= 0 || day > getMaxDay()) {
24 cout << "Invalid date: ";
25 show();
26 cout << endl;
27 exit(1);
28 }
29 int years = year - 1;
30 totalDays = years * 365 + years / 4 - years / 100 + years / 400
31 + DAYS_BEFORE_MONTH[month - 1] + day;
32 if (isLeapYear() && month > 2) totalDays++;
33 }
account.h
1 #pragma once
2 #include "date.h"
3 #include <string>
4
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
14 void record(const Date& date, double amount, const std::string& desc);
15 void error(const std::string& msg) const;
16 double accumulate(const Date& date) const {
17 return accumulation + balance * date.distance(lastDate);
18 }
19
20 public:
21 SavingsAccount(const Date& date, const std::string& id, double rate);
22 const std::string& getId() const { return id; }
23 double getBalance() const { return balance; }
24 double getRate() const { return rate; }
25 static double getTotal() { return total; }
26
27 void deposit(const Date& date, double amount, const std::string& desc);
28 void withdraw(const Date& date, double amount, const std::string& desc);
29 void settle(const Date& date);
30 void show() const;
31 };
account.cpp
1 #include "account.h"
2 #include <cmath>
3 #include <iostream>
4
5 using namespace std;
6
7 double SavingsAccount::total = 0;
8
9 SavingsAccount::SavingsAccount(const Date& date, const string& id, double rate) :
10 id{ id }, balance{ 0 }, rate{ rate }, lastDate{ date }, accumulation{ 0 } {
11 date.show();
12 cout << "\t#" << id << "created" << endl;
13 }
14
15 void SavingsAccount::record(const Date& date, double amount, const string& desc) {
16 accumulation = accumulate(date);
17 lastDate = date;
18 amount = floor(amount * 100 + 0.5) / 100;
19 balance += amount;
20 total += amount;
21 date.show();
22 cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
23 }
24
25 void SavingsAccount::error(const string& msg) const {
26 cout << "Error(#" << id << "):" << msg << endl;
27 }
28
29 void SavingsAccount::deposit(const Date& date, double amount, const string& desc) {
30 record(date, amount, desc);
31 }
32
33 void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) {
34 if (amount > getBalance())
35 error("not enough money");
36 else
37 record(date, -amount, desc);
38 }
39
40 void SavingsAccount::settle(const Date& date) {
41 double interest = accumulate(date) * rate
42 / date.distance(Date(date.getYear() - 1, 1, 1));
43 if (interest != 0)
44 record(date, interest, "interest");
45 accumulation = 0;
46 }
47
48 void SavingsAccount::show() const {
49 cout << id << "\tBalance:" << balance;
50 }
6_25.cpp
1 #include "account.h"
2 #include <iostream>
3
4 using namespace std;
5
6 int main() {
7 Date date(2008, 11, 1);
8 SavingsAccount accounts[] = {
9 SavingsAccount(date, "03755217", 0.015),
10 SavingsAccount(date, "02342342", 0.015)
11 };
12 const int n = sizeof(accounts) / sizeof(SavingsAccount);
13
14 accounts[0].deposit(Date(2008, 11, 5), 5000, "salary");
15 accounts[1].deposit(Date(2008, 11, 25), 10000, "sell stock 0323");
16
17 accounts[0].deposit(Date(2008, 12, 5), 5500, "salary");
18 accounts[1].withdraw(Date(2008, 12, 20), 4000, "buy a laptop");
19
20 cout << endl;
21
22 for (int i = 0; i < n; i++) {
23 accounts[i].settle(Date(2009, 1, 1));
24 accounts[i].show();
25 cout << endl;
26 }
27
28 cout << "Total:" << SavingsAccount::getTotal() << endl;
29 }
运行结果截图:
标签：std,const,cout,对象,void,编程,int,实验,include From： https://www.cnblogs.com/forgiver/p/18525846