Effective C++学习笔记之copy构造函数和default函数和copy赋值函数(operator=)

class A {
};

class A
{
public:
    A(){}    //default函数
    ~A(){}   //析构函数
    A(const A& a) {}  //copy构造函数
    A& operator= (const A& a) {} //copy assignment操作符
};

A a1;  //default构造函数
A a2(a1); //copy构造函数
a1 = a2; //copy assignment操作符
A a3 = a1; //copy构造函数

#include <iostream>
using namespace std;
class A
{
public:
    A() {
        std::cout << "A(){}" << std::endl;
    }
    ~A() {
        std::cout << "~A()" << std::endl;
    }
    A(const A& a) {
        std::cout << "A(const A&)" << std::endl;
    }
    A& operator= (const A& a) {
        std::cout << "A& operator=(const A& a)" << std::endl;
    }
};
int main()
{
    A a1;
    A a2(a1);
    a1 = a2;
    A a3 = a1;
    return 0;
}

A(){}
A(const A&)
A& operator=(const A& a)
A(const A&)
~A()
~A()
~A()