c++移动构造和赋值的样例

#include <iostream>class MyResource {
public:// 默认构造函数MyResource(size_t size = 0) : m_size(size), m_data(size ? new int[size] : nullptr) {std::cout << "Default constructor called\n";}// 析构函数~MyResource() {delete[] m_data;std::cout << "Destructor called\n";}// 拷贝构造函数MyResource(const MyResource& other) : m_size(other.m_size), m_data(other.m_size ? new int[other.m_size] : nullptr) {std::copy(other.m_data, other.m_data + m_size, m_data);std::cout << "Copy constructor called\n";}// 拷贝赋值运算符MyResource& operator=(const MyResource& other) {if (this == &other)return *this;delete[] m_data;m_size = other.m_size;m_data = other.m_size ? new int[other.m_size] : nullptr;std::copy(other.m_data, other.m_data + other.m_size, m_data);std::cout << "Copy assignment operator called\n";return *this;}// 移动构造函数MyResource(MyResource&& other) noexcept : m_size(other.m_size), m_data(other.m_data) {other.m_size = 0;other.m_data = nullptr;std::cout << "Move constructor called\n";}// 移动赋值运算符MyResource& operator=(MyResource&& other) noexcept {if (this == &other)return *this;delete[] m_data;m_size = other.m_size;m_data = other.m_data;other.m_size = 0;other.m_data = nullptr;std::cout << "Move assignment operator called\n";return *this;}// 获取大小size_t size() const {return m_size;}// 检查数据指针const int* data() const {return m_data;}private:size_t m_size;  // 存储大小int* m_data;    // 指向资源的指针
};int main() {MyResource res1(10);          // 调用默认构造函数MyResource res2 = std::move(res1); // 调用移动构造函数MyResource res3;              // 调用默认构造函数res3 = std::move(res2);     // 调用移动赋值运算符return 0;
}

• 默认构造函数: 初始化资源（如果有大小）。
• 析构函数: 释放动态分配的资源。
• 拷贝构造函数: 深拷贝资源。
• 拷贝赋值运算符: 先删除已有资源再深拷贝新资源。
• 移动构造函数: 转移资源所有权，将源对象的资源指针置空。
• 移动赋值运算符: 先删除已有资源，接着转移新资源的所有权并将源对象的资源指针置空。