class A
{
	friend ostream& operator<<(ostream& os,const A&);
	friend A operator+(const A&,const A&);
public:
	A(int i=0):m_i(i){cout<<"A(int i=0)"<<endl;}
	A(const A& a)
	{
		m_i=a.m_i;
		cout<<"A(const A&)"<<endl;}
	const A& operator=(const A& a)
	{
		cout<<"const A& operator=(const A& a)"<<endl;
		m_i=a.m_i;
		return *this;
	}
	~A()
	{cout<<"~A()"<<endl;}
private:
	int m_i;
};
A operator+(const A& a,const A& b)
{
	A c=a.m_i+b.m_i;
	return c;
}
ostream& operator<<(ostream& os,const A& a)
{
	os<<"ostream& operator<<(operator& os,const A&)"<<endl;
	cout<<a.m_i<<endl;
	return os;
}
const A& f(const A& a)
{
	return a;
}
const A func(const A a)
{
	return a;
}
int main(int argc,char**argv)
{
	/*const A& a=A();
	cout<<"_______________________"<<endl;
	cout<<f(A())<<endl;
	cout<<"-----------------------"<<endl;
	const A b=func(A());
	cout<<"as"<<endl;*/
	A a1(3),a2(4);
	a1+a2;
	cout<<"仅仅是区分一下是否产生临时对象："<<endl;
	A c=a1+a2;
	cout<<c<<endl;
	return 0;
}

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