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 }
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：
问题：
问题1：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？
答：自定义了两个类Button和Window。用的了标准库类string和vector。Window和Button类之间存在组合关系。
问题2：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。
适合添加const，因为它不会修改类的状态。适合添加inline，实现简单，代码量少。
问题3：类Window的定义中，有这样一行代码，其功能是？
创建了一个名为s的string对象，初始化又40个‘*’字符组成的字符串
任务2
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：
任务3
vectorlnt.hpp
1 #pragma once
2
3 #include <iostream>
4 #include <cassert>
5
6 using std::cout;
7 using std::endl;
8 // 动态int数组对象类
9 class vectorInt{
10 public:
11 vectorInt(int n);
12 vectorInt(int n, int value);
13 vectorInt(const vectorInt &vi);
14 ~vectorInt();
15
16 int& at(int index);
17 const int& at(int index) const;
18
19 vectorInt& assign(const vectorInt &v);
20 int get_size() const;
21 private:
22 int size;
23 int *ptr; // ptr指向包含size个int的数组
24 };
25 vectorInt::vectorInt(int n): size{n}, ptr{new int[size]} {
26 }
27 vectorInt::vectorInt(int n, int value): size{n}, ptr{new int[size]} {
28 for(auto i = 0; i < size; ++i)
29 ptr[i] = value;
30 vectorInt::vectorInt(const vectorInt &vi): size{vi.size}, ptr{new int[size]} {
31 for(auto i = 0; i < size; ++i)
32 ptr[i] = vi.ptr[i];
33 }
34 vectorInt::~vectorInt() {
35 delete [] ptr;
36 }
37
38 const int& vectorInt::at(int index) const {
39 assert(index >= 0 && index < size);
40
41 return ptr[index];
42 }
43
44 int& vectorInt::at(int index) {
45 assert(index >= 0 && index < size);
46
47 return ptr[index];
48 }
49 vectorInt& vectorInt::assign(const vectorInt &v) {
50 delete[] ptr; // 释放对象中ptr原来指向的资源
51
52 size = v.size;
53 ptr = new int[size];
54
55 for(int i = 0; i < size; ++i)
56 ptr[i] = v.ptr[i];
57
58 return *this; //this现在指向正在初始化的对象，*this即为这个对象
59 }
60
61 int vectorInt::get_size() const {
62 return size;
63 }
task3.cpp
1 #include "vectorInt.hpp"
2 #include <iostream>
3
4 using std::cin;
5 using std::cout;
6 void output(const vectorInt &vi) {
7 for(auto i = 0; i < vi.get_size(); ++i)
8 cout << vi.at(i) << ", ";
9 cout << "\b\b \n";
10 }
11
12
13 void test1() {
14 int n;
15 cout << "Enter n: ";
16 cin >> n;
17
18 vectorInt x1(n);
19 for(auto i = 0; i < n; ++i)
20 x1.at(i) = i*i;
21 cout << "x1: "; output(x1);
22
23 vectorInt x2(n, 42);
24 vectorInt x3(x2);
25 x2.at(0) = -999;
26 cout << "x2: "; output(x2);
27 cout << "x3: "; output(x3);
28 }
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：
问题：
1.深复制
2.不能，会有潜在安全隐患
3.返回值类型为 vectorInt& 时：返回当前对象的引用 *this，意味着调用 assign() 后，调用者获得的是调用对象本身。这允许方法链调用
标签：const,cout,int,实验,vectorInt,ptr,size From： https://www.cnblogs.com/rxt711/p/18525747