构造函数/拷贝构造函数/赋值构造函数

#include <iostream>#include <vector>using namespace std;class A{public:A(){ cout << "默认" << endl; };A(int id) :m_id(id){ cout << "A::A() " <<m_id<< endl; };~A(){ cout << "A::~A() " <<m_id<< endl;};A(const A&rhs){m_id = rhs.m_id;cout << "A copy constructor" << endl; };A& operator = (const A&rhs){ m_id = rhs.m_id;cout << "A copy assignment" << endl; return *this;};private:int m_id;};void f(A a){return;}void g(A &a){return;}A h(A a){return a;}int main(){A aa(1);//f(aa);//g(aa);A bb = aa;bb = h(aa);return 0;}//程序运行结果//A::A()                     A aa;  aa的构造函数//A copy constructor         A bb == aa;//A copy constructor 参数传递，//A copy constructor 值传给临时变量//A::~A() 临时变量销毁//A copy assignment 赋值构造//A::~A() bb//A::~A()              //A::~A()                  //请按任意键继续. . .