#include <iostream>using namespace std;class A
{
private:int* n;public:A(){n = new int[10];n[0] = 1;cout<<"constructor is called\n";}A(const A& a){n = a.n;cout<<"copy constructor is called\n";}~A(){cout<<"destructor is called\n";delete n;}void get(){cout<<"n[0]: "<<n[0]<<endl;}
};int main()
{A* a = new A();A b = *a;delete a;b.get();return 0;
}

#include <iostream>
#include <string.h>
using namespace std;class A
{
private:int* n;public:A(){n = new int[10];n[0] = 1;cout<<"constructor is called\n";}A(const A& a){n = new int[10];memcpy(n, a.n, 10);  //通过按字节拷贝，将堆中一块内存存储到另一块内存cout<<"copy constructor is called\n";}~A(){cout<<"destructor is called\n";delete n;}void get(){cout<<"n[0]: "<<n[0]<<endl;}
};int main()
{A* a = new A();A b = *a;delete a;b.get();return 0;
}

#include <iostream>
#include <string.h>
using namespace std;class A
{
private:int* n;public:A(){n = new int[10];n[0] = 1;cout<<"constructor is called\n";}A(const A& a) //拷贝构造函数的参数一定是引用，不能不是引用，不然会出现无限递归
    {n = new int[10];memcpy(n, a.n, 10);  //通过按字节拷贝，将堆中一块内存存储到另一块内存cout<<"copy constructor is called\n";}A& operator=(const A& a)  //记住形参和返回值一定要是引用类型，否则传参和返回时会自动调用拷贝构造函数{if(this == &a)     //为什么需要进行自我赋值判断呢？因为下面要进行释放n的操作，如果是自我赋值，而没有进行判断的话，那么就会出现讲一个释放了的内存赋给一个指针return *this;if(n != NULL){delete n;n == NULL;   //记住释放完内存将指针赋为NULL}n = new int[10];memcpy(n, a.n, 10);cout<<"assign constructor is called\n";return *this;}~A(){cout<<"destructor is called\n";delete n;　　　　　n = NULL;  //记住释放完内存将指针赋为NULL}void get(){cout<<"n[0]: "<<n[0]<<endl;}
};int main()
{A* a = new A();A* b =  new A();*b = *a;delete a;b->get();
return 0;
}

#include <iostream>
#include <string.h>
using namespace std;class A
{
private:int* n;public:A(){n = new int[10];n[0] = 1;cout<<"constructor is called\n";}A(const A& a) //拷贝构造函数的参数一定是引用，不能不是引用，不然会出现无限递归
    {n = new int[10];memcpy(n, a.n, 10);  //通过按字节拷贝，将堆中一块内存存储到另一块内存cout<<"copy constructor is called\n";}A operator=(const A a)   //传参和返回值设置错误{if(this == &a)return *this;if(n != NULL){delete n;n == NULL;}n = new int[10];memcpy(n, a.n, 10);cout<<"assign constructor is called\n";return *this;}~A(){cout<<"destructor is called\n";delete n;}void get(){cout<<"n[0]: "<<n[0]<<endl;}
};int main()
{A* a = new A();A* b =  new A();*b = *a;delete a;b->get();while(1){}return 0;
}