副本构造器（重载赋值号）

版权声明：根号v587版权所有 https://blog.csdn.net/hcmdghv587/article/details/81913960

#include <iostream>
using namespace std;
class Array
{
public:
    int *array;
    Array(void);
    Array(const Array &rhs);
    ~Array();
    Array & operator=(const Array &rhs);
    void create(int length);
    int length;
    int message;
};

Array::Array(void)
{
    length = 0;
    array = NULL;
    cout << "进入构造器" << endl;
}
Array::Array(const Array &rhs)  //副本构造器
{
    cout << "进入副本构造器" << endl;
    this -> array = NULL;
    *this = rhs;    //!!!
}
void Array::create(int length)
{
    array = new int[length];
    this -> length = length;
    for (int i = 0; i < length; i++)
    {
        array[i] = i;
    }
}
Array & Array::operator=(const Array &rhs)   //重载赋值号
{
    if (this != &rhs)
    {
        if (array != NULL)
        {
            delete [] array;
        }
        length = rhs.length;
        array = new int[length];
        for (int i = 0; i < length; i++)
        {
            array[i] = rhs.array[i];
        }
        cout << "拷贝成功！" << endl;
    }
    else
    {
        cout << "无需拷贝" << endl;
    }
    return *this;   //!!!
}
Array::~Array()
{
    if (array != NULL)
    {
        delete [] array;
    }
    cout << "进入析构器" << endl;
}

int main()
{
    Array a1, a2;
    a1.create(10);
    a1.message = 13;
    a2 = a1;
    cout << "a2.message=" << a2.message << endl;
    //message需要手动复制
    a2 = a2;
    a1.array[5] = 99;
    cout << "a1.array[5]=" << a1.array[5] << endl;
    cout << "a2.array[5]=" << a2.array[5] << endl;
    Array a3 = a1;
    cout << "a3.message=" << a3.message << endl;
    a1.array[5] = 66;
    cout << "a3.array[5]=" << a3.array[5] << endl;
    return 0;
}