#include<iostream>

 using namespace std;

 class Test {

     friend Test addTest(Test &obj1, Test &obj2);

 //    friend Test operator+(Test &obj1, Test &obj2);

 public:

     Test(int a = , int b = )

     {

         this->a = a;

         this->b = b;

     }

     void display()

     {

         cout << "a:" << a << " b:" << b << endl;

     }

 public:

     Test operator+(Test &obj)

     {

         Test temp(this->a+obj.a,this->b+obj.b);

         return temp;

     }

 private:

     int a;

     int b;

 };

 Test addTest(Test &obj1, Test &obj2)

 {

     Test temp(obj1.a + obj2.a, obj1.b + obj2.b);

     return temp;

 }

 //Test operator+(Test &obj1, Test &obj2)

 //{

 //    Test temp(obj1.a + obj2.a, obj1.b + obj2.b);

 //    return temp;

 //}

 int main()

 {

     /* 第一个测试

     Test t1(1, 2), t2(3, 4);

     Test t3 = addTest(t1, t2);

     Test t4 = t1+t2;//err

     t3.display();

     */

     /* 第二个测试

     Test t1(1, 2), t2(3, 4);

     Test t3 = operator+(t1, t2);

     Test t4 = t1+t2;

     t3.display();

     t4.display();

     */

     /*第三个测试

     Test t1(1, 2), t2(3, 4);

 //    Test t3 = operator+(t1, t2);err

     Test t3 = t1.operator+(t2);

     Test t4 = t1+t2;

     t3.display();

     t4.display();

     */

     cout << "hello world!\n";

     return ;

 }