C++笔记：move语义与右值引用

来自《c++标准库 第2版》

1. Move语义与右值引用

2. 右值、左值引用的重载规则

3. 返回右值引用

4. 测试代码

#include <iostream>
#include <chrono>
#include <fstream>


class MyBinData
{
public:
    MyBinData()
    {
        m_pBuffer = nullptr;
        m_nBytes = 0;
    }


    MyBinData(const char* pData, uint32_t nSize)
    {
        m_pBuffer = new char[nSize];
        memcpy_s(m_pBuffer, nSize, pData, nSize);
        m_nBytes = nSize;
    }

    virtual ~MyBinData()
    {
        if (m_pBuffer)
        {
            delete[] m_pBuffer;
            m_pBuffer = 0;
            m_nBytes = 0;
        }
        std::cout << "deconstructor is called" << std::endl;
    }

    MyBinData(const MyBinData& other)
    {
        m_nBytes = other.m_nBytes;
        if (m_nBytes > 0)
        {
            m_pBuffer = new char[other.m_nBytes];
            memcpy_s(m_pBuffer, m_nBytes, other.m_pBuffer, other.m_nBytes);
        }
        else
        {
            m_pBuffer = nullptr;
        }
    }


    MyBinData(MyBinData&& other) noexcept
    {
        m_pBuffer = other.m_pBuffer;
        m_nBytes = other.m_nBytes;

        other.m_pBuffer = nullptr;
        other.m_nBytes = 0;
    }

    MyBinData& operator=(MyBinData&& other) noexcept
    {
        if (this == &other)
        {
            return *this;
        }

        delete[] m_pBuffer;

        m_pBuffer = other.m_pBuffer;
        m_nBytes = other.m_nBytes;

        other.m_pBuffer = nullptr;
        other.m_nBytes = 0;

        return *this;
    }

    MyBinData& operator=(const MyBinData& other)
    {
        if (this == &other)
        {
            return *this;
        }

        if (m_pBuffer) delete[] m_pBuffer;

        m_nBytes = other.m_nBytes;
        if (m_nBytes > 0)
        {
            m_pBuffer = new char[other.m_nBytes];
            memcpy_s(m_pBuffer, m_nBytes, other.m_pBuffer, other.m_nBytes);
        }
        else
        {
            m_pBuffer = nullptr;
        }
        return *this;
    }

private:
    char* m_pBuffer;
    uint32_t m_nBytes;
};


int main()
{
    MyBinData mData("aaaaaa", 7);

    MyBinData mData2 = std::move(mData);

    std::cout << "ending" << std::endl;

    return 0;
}