深入C++混乱地带 002 你了解拷备构造函数吗

#include <iostream>usingnamespacestd;
structA {
public:
A() {
cout<<"call ()"<<endl;
    }
~A()
    {
cout<<"call ~"<<endl;
    }
A(constA&a)
    {
v=a.v;
cout<<"call (&)"<<endl;
    }
voidoperator= (constA&a)
    {
v=a.v;
cout<<"call =(&)"<<endl;
    }
intv=++s;
staticints;
};
intA::s=0;
AGetA()
{
Aa;
cout<<a.v<<endl;
returna;
}
intmain()
{
Aa1=GetA();
Aa2(GetA());
Aa3{GetA()};
cout<<"a1 "<<a1.v<<endl;
cout<<"a2 "<<a2.v<<endl;
cout<<"a3 "<<a3.v<<endl;
cout<<A::s<<endl; // ?return0;
}