实验3
实验任务1：
button.hpp:
#pragma once #include <iostream> #include <string> class Button { public: Button(const std::string &label_); const std::string& get_label() const; void click(); private: std::string label; }; Button::Button(const std::string &label_): label(label_) { } inline const std::string& Button::get_label() const { return label; } inline void Button::click() { std::cout << "Button '" << label << "' clicked\n"; }
window.hpp
#pragma once #include <iostream> #include <vector> #include <algorithm> #include "button.hpp" // 窗口类 class window { public: window(const std::string &title_); void display() const; void close(); void add_button(const std::string &label_); void click_button(const std::string &label); private: bool has_button(const std::string &label) const; private: std::string title; std::vector<Button> buttons; }; window::window(const std::string &title_): title(title_) { buttons.push_back(Button("close")); } inline void window::display() const { // 显示方法实现（图片中未完整显示） } inline void window::close() { std::cout << "Close window '" << title << "'" << std::endl; click_button("close"); } inline bool window::has_button(const std::string &label) const { for(const auto &button: buttons) if(button.get_label() == label) return true; return false; } inline void window::add_button(const std::string &label) { if(has_button(label)) std::cout << "button " << label << " already exists!\n"; else buttons.push_back(Button(label)); } inline void window::click_button(const std::string &label) { for(auto &button:buttons) if(button.get_label() == label) { button.click(); return; } std::cout << "no button: " << label << std::endl; }
test.cpp
#include "window.hpp" #include <iostream> void test(){ window w("Demo"); w.add_button("add"); w.add_button("remove"); w.add_button("modify"); w.add_button("add"); w.display(); w.close(); } int main() { std::cout << "用组合类模拟简单GUI:\n"; test(); }
运行结果：
问题1：
是组合关系
问题2：
优点是更加的灵活，缺点是破坏了封装性
问题3：
接口2的安全性比接口1更高，但是性能没有接口一好
问题4：
第一种写法先构造在拷贝，第2种直接在内存空间中构造了button对象
实验任务2：
#include<iostream> #include<vector> void test1(); void test2(); void output1(const std::vector<int>&v); void output2(const std::vector<int>&v); void output3(const std::vector<std::vector<int>>&v); int main(){ std::cout<<"深复制验证1：标准库vector<int>\n"; test1(); std::cout<<"\n深复制验证2:标准库vector<int>\n"; test2(); } void test1() { std::vector<int> v1(5,42); const std::vector<int> v2(v1); std::cout<<"********拷贝构造后*********\n"; std::cout<<"v1: ";output1(v1); std::cout<<"v2: ";output2(v2); v1.at(0)=-1; std::cout<<"*****修改v1[0]*********\n"; std::cout<<"v1: ";output1(v1); std::cout<<"v2: ";output1(v2); } void test2() { std::vector<std::vector<int>>v1{{1,2,3},{4,5,6,7}}; const std::vector<std::vector<int>>v2(v1); std::cout<<"*******拷贝构造后**********\n"; std::cout<<"v1:\n";output3(v1); std::cout<<"v2:\n";output3(v2); } void output1(const std::vector<int>&v){ if(v.size()==0){ std::cout<<'\n'; return; } std::cout<<v.at(0); for(auto i=1;i<v.size();++i) std::cout<<","<<v.at(i); std::cout<<'\n'; } void output2(const std::vector<int>&v) { if(v.size()==0) { std::cout<<'\n'; return; } auto it=v.begin(); std::cout<<*it; for(it=v.begin()+1;it!=v.end();++it) { std::cout<<","<<*it; std::cout<<'\n'; } } void output3(const std::vector<std::vector<int>>&v) { if(v.size()==0) { std::cout<<'\n'; return; } for(auto &i:v) output2(i); }
实验结果：
问题1：
v1包含5个
v2包含5个42的值
问题2：
v1.size()=2
v2.size()=2
v1[0].size()=3
问题3：
at()进行了边界检查更加安全
[]不进行边界检查性能较好
问题4：
1，能输出-1，v1.at()在vector内部第一个使用
2.具有更高的性能，不会产生临时对象
但是不能修改被应用的对象
问题5：
1.深复制
2.int&;vector(int)&;需要提供带const的修饰版本
实验任务3：
vectorint.hpp:
#pragma once #include <iostream> // 动态int数组对象类 class vectorInt { public: vectorInt(); vectorInt(int n_); vectorInt(int n_, int value); vectorInt(const vectorInt &v1); ~vectorInt(); int size() const; int& at(int index); const int& at(int index) const; vectorInt& assign(const vectorInt &v1); int* begin(); int* end(); const int* begin() const; const int* end() const; private: int n; // 当前数据项个数 int *ptr; // 数据区 }; vectorInt::vectorInt() : n(0), ptr(nullptr) { } vectorInt::vectorInt(int n_) : n(n_), ptr(new int[n]) { } vectorInt::vectorInt(int n_, int value) : n(n_), ptr(new int[n_]) { for (int i = 0; i < n_; ++i) ptr[i] = value; } vectorInt::vectorInt(const vectorInt &v1) : n(v1.n), ptr(new int[v1.n]) { for (int i = 0; i < v1.n; ++i) ptr[i] = v1.ptr[i]; } vectorInt::~vectorInt() { delete[] ptr; } int vectorInt::size() const { return n; } const int& vectorInt::at(int index) const { if (index < 0 || index >= n) { std::cerr << "IndexError: index out of range\n"; std::exit(1); } return ptr[index]; } int& vectorInt::at(int index) { if (index < 0 || index >= n) { std::cerr << "IndexError: index out of range\n"; std::exit(1); } return ptr[index]; } vectorInt& vectorInt::assign(const vectorInt &v1) { if (this == &v1) return *this; int *ptr_tmp = new int[v1.n]; for (int i = 0; i < v1.n; ++i) ptr_tmp[i] = v1.ptr[i]; delete[] ptr; n = v1.n; ptr = ptr_tmp; return *this; } int* vectorInt::begin() { return ptr; } int* vectorInt::end() { return ptr + n; } const int* vectorInt::begin() const { return ptr; } const int* vectorInt::end() const { return ptr + n; }
test.cpp:
#include <iostream> #include "vectorInt.hpp" void test1(); void test2(); void output1(const vectorInt &v1); void output2(const vectorInt &v1); int main() { std::cout << "测试1: \n"; test1(); std::cout << "\n测试2: \n"; test2(); } void test1() { int n; std::cout << "Enter n: "; std::cin >> n; vectorInt x1(n); for (auto i = 0; i < n; ++i) x1.at(i) = (i + 1) * 10; std::cout << "x1: "; output1(x1); vectorInt x2(n, 42); vectorInt x3(x2); x2.at(0) = -1; std::cout << "x2: "; output1(x2); std::cout << "x3: "; output1(x3); } void test2() { const vectorInt x(5, 42); vectorInt y; y.assign(x); std::cout << "x: "; output2(x); std::cout << "y: "; output2(y); } // 使用 at() + 循环输出 vectorInt 对象数据项 void output1(const vectorInt &v1) { if (v1.size() == 0) { std::cout << "\n"; return; } std::cout << v1.at(0); for (auto i = 1; i < v1.size(); ++i) std::cout << ", " << v1.at(i); std::cout << "\n"; } // 使用迭代器 + 循环输出 vectorInt 对象数据项 void output2(const vectorInt &v1) { if (v1.size() == 0) { std::cout << "\n"; return; } auto it = v1.begin(); std::cout << *it; for (it = v1.begin() + 1; it != v1.end(); ++it) std::cout << ", " << *it; std::cout << "\n"; }
实验结果：、
问题1：
1.缺少自生赋值的检查
2.参数名不一致
3.内存释放后无法被恢复
问题2：
static_cast<const vectorInt*>(this)将this指针从vectorint*转化为const vectorint*,避免了代码的重复
const_cast<int&>移除返回值const限定，匹配非const版本的返回类型
问题3：
非const版本：用于需要修改容器内容的场景
const的版本：用于只读访问保证内容不会修改
迭代器本质是提供访问接口
问题4：
std::fill_n(ptr,n,value)
将ptr开始的前n个元素都设置为value
手动循环:for(int i=0;i<n;++i)ptr[i]=value;
std::copy_n(v1.ptr,v1.n,ptr)
从v1.ptr复制v1.n个元素到ptr
手动循环：for(int i=0;i<v1.n;++i)ptr[i]=v1.ptr[i];
std::copy_n(v1.ptr,v1.n,ptr_tmp)
复制数据代买更加简洁不易出错
实验任务4：
matrix.hpp
#pragma once class Matrix { public: Matrix(int rows_, int cols_, double value = 0); Matrix(int rows_, double value = 0); Matrix(const Matrix &x); ~Matrix(); void set(const double *pvalue, int size); void clear(); const double& at(int i, int j) const; double& at(int i, int j); int rows() const; int cols() const; void print() const; private: int n_rows; int n_cols; double *ptr; };
matrix.cpp
#include <iostream> #include <cstdlib> #include "matrix.hpp" Matrix::Matrix(int rows_, int cols_, double value) : n_rows(rows_), n_cols(cols_) { if (rows_ <= 0 || cols_ <= 0) { std::cerr << "Error: Invalid matrix dimensions\n"; std::exit(1); } ptr = new double[n_rows * n_cols]; for (int i = 0; i < n_rows * n_cols; ++i) { ptr[i] = value; } } Matrix::Matrix(int rows_, double value) : n_rows(rows_), n_cols(rows_) { if (rows_ <= 0) { std::cerr << "Error: Invalid matrix dimensions\n"; std::exit(1); } ptr = new double[n_rows * n_cols]; for (int i = 0; i < n_rows * n_cols; ++i) { ptr[i] = value; } } Matrix::Matrix(const Matrix &x) : n_rows(x.n_rows), n_cols(x.n_cols) { ptr = new double[n_rows * n_cols]; for (int i = 0; i < n_rows * n_cols; ++i) { ptr[i] = x.ptr[i]; } } Matrix::~Matrix() { delete[] ptr; } void Matrix::set(const double *pvalue, int size) { if (size != n_rows * n_cols) { std::cerr << "Error: Size mismatch in set function\n"; std::exit(1); } for (int i = 0; i < size; ++i) { ptr[i] = pvalue[i]; } } void Matrix::clear() { for (int i = 0; i < n_rows * n_cols; ++i) { ptr[i] = 0; } } const double& Matrix::at(int i, int j) const { if (i < 0 || i >= n_rows || j < 0 || j >= n_cols) { std::cerr << "Error: Index out of range\n"; std::exit(1); } return ptr[i * n_cols + j]; } double& Matrix::at(int i, int j) { if (i < 0 || i >= n_rows || j < 0 || j >= n_cols) { std::cerr << "Error: Index out of range\n"; std::exit(1); } return ptr[i * n_cols + j]; } int Matrix::rows() const { return n_rows; } int Matrix::cols() const { return n_cols; } void Matrix::print() const { for (int i = 0; i < n_rows; ++i) { std::cout << at(i, 0); for (int j = 1; j < n_cols; ++j) { std::cout << ", " << at(i, j); } std::cout << '\n'; } }
task4.cpp
#include <iostream> #include <cstdlib> #include "matrix.hpp" void test1(); void test2(); void output(const Matrix &m, int row_index); int main() { std::cout << "测试1: \n"; test1(); std::cout << "\n测试2: \n"; test2(); } void test1() { double x[1000] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; int n, m; std::cout << "Enter n and m: "; std::cin >> n >> m; Matrix m1(n, m); m1.set(x, n*m); Matrix m2(m, n); m2.set(x, m*n); Matrix m3(n); m3.set(x, n*n); std::cout << "矩阵对象m1: \n"; m1.print(); std::cout << "矩阵对象m2: \n"; m2.print(); std::cout << "矩阵对象m3: \n"; m3.print(); } void test2() { Matrix m1(2, 3, -1); const Matrix m2(m1); std::cout << "矩阵对象m1: \n"; m1.print(); std::cout << "矩阵对象m2: \n"; m2.print(); m1.clear(); m1.at(0, 0) = 1; std::cout << "m1更新后: \n"; std::cout << "矩阵对象m1第0行: "; output(m1, 0); std::cout << "矩阵对象m2第0行: "; output(m2, 0); } void output(const Matrix &m, int row_index) { if (row_index < 0 || row_index >= m.rows()) { std::cerr << "IndexError: row index out of range\n"; std::exit(1); } std::cout << m.at(row_index, 0); for (int j = 1; j < m.cols(); ++j) { std::cout << ", " << m.at(row_index, j); } std::cout << '\n'; }
实验结果
实验任务5：
contact.hpp
#pragma once #include <iostream> #include <string> class Contact { public: Contact(const std::string &name_, const std::string &phone_); const std::string &get_name() const; const std::string &get_phone() const; void display() const; private: std::string name; // 必填项 std::string phone; // 必填项 }; Contact::Contact(const std::string &name_, const std::string &phone_):name(name_), phone(phone_) { } const std::string& Contact::get_name() const { return name; } const std::string& Contact::get_phone() const { return phone; } void Contact::display() const { std::cout << name << ", " << phone; }
contactBook.hpp
#pragma once #include <iostream> #include <string> #include <vector> #include <algorithm> #include "contact.hpp" class ContactBook { public： void add(const std::string &name, const std::string &phone); void remove(const std::string &name); void find(const std::string &name) const; void display() const; size_t size() const; private: int index(const std::string &name) const; void sort(); private: std::vector<Contact> contacts; }; void ContactBook::add(const std::string &name, const std::string &phone) { if(index(name) == -1) { contacts.push_back(Contact(name, phone)); std::cout << name << " add successfully.\n"; sort(); return; } std::cout << name << " already exists. fail to add!\n"; } void ContactBook::remove(const std::string &name) { int i = index(name); if(i == -1) { std::cout << name << " not found, fail to remove!\n"; return; } contacts.erase(contacts.begin() + i); std::cout << name << " remove successfully.\n"; } void ContactBook::find(const std::string &name) const { int i = index(name); if(i == -1) { std::cout << name << " not found!\n"; return; } contacts[i].display(); std::cout << '\n'; } void ContactBook::display() const { for(auto &c: contacts) { c.display(); std::cout << '\n'; } } size_t ContactBook::size() const { return contacts.size(); } int ContactBook::index(const std::string &name) const { for (size_t i = 0; i < contacts.size(); ++i) { if (contacts[i].get_name() == name) { return static_cast<int>(i); } } return -1; } void ContactBook::sort() { std::sort(contacts.begin(), contacts.end(), [](const Contact &a, const Contact &b) { return a.get_name() < b.get_name(); }); }
task5.cpp
#include "contactBook.hpp" #include <iostream> void test() { ContactBook contactbook; std::cout << "1. add contacts\n"; contactbook.add("Bob", "18199357253"); contactbook.add("Alice", "17300886371"); contactbook.add("Linda", "18184538072"); contactbook.add("Alice", "17300886371"); std::cout << "\n2. display contacts\n"; std::cout << "There are " << contactbook.size() << " contacts.\n"; contactbook.display(); std::cout << "\n3. find contacts\n"; contactbook.find("Bob"); contactbook.find("David"); std::cout << "\n4. remove contact\n"; contactbook.remove("Bob"); contactbook.remove("David"); } int main() { test(); return 0; }
实验结果：
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